A method for molding an integral tandem composite hollow skeleton

Abstract

This invention belongs to the field of composite material parts processing technology, and discloses an integral tandem composite hollow skeleton molding method, including mold design and manufacturing, sample design and manufacturing, manufacturing airbags using the mold and sample, laying composite material fabric layers in the mold, placing airbags in the laid composite material fabric layers, wrapping the composite material fabric layers to wrap the airbags, pre-molding and closing the mold, providing a vacuum environment and a thermosetting environment for the closed mold, opening the mold, removing the airbags first, and then removing the product; wherein, the airbags are silicone capsules made of silicone, and the silicone capsules have support columns inside. The silicone capsule of this invention serves as both a layup mold and a pressure transmission medium, facilitating the product layup process, simplifying the operation procedure, and improving operability. A support structure is added to the airbag, which is connected to one side of the capsule and separated from the other side. This structure enhances the rigidity of the silicone capsule, enabling it to function as a layup mold in the product application process. The airbag structure with a break point proposed in this invention allows the tandem integral airbags to be deployed intact after product manufacturing, achieving reusability and cost reduction.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material part processing, and relates to a processing method for integral tandem composite materials, specifically to a forming method for an integral tandem composite hollow skeleton. Background Art

[0002] The integral tandem hollow skeleton is a typical skeleton structure, which can achieve the best cost performance between structural rigidity and weight to the greatest extent. Under the condition of achieving structural rigidity, the integral tandem structure avoids connection areas, connection area reinforcement, and standard parts, and can significantly reduce the structural weight, which is the optimal solution for the design of the tandem skeleton structure.

[0003] In order to meet the structural assembly requirements, the integral tandem composite hollow skeleton structure generally includes an integral tandem structure, a "convex" cross-sectional structure, a semi-"convex" cross-sectional structure, a "C"-shaped cross-sectional structure, a "ji" -shaped cross-sectional structure, etc., and the manufacturing difficulty is large; for the traditional tandem hollow skeleton, the tandem skeleton is divided into front / rear two skeletons and multiple skeleton connectors, and the front / rear skeletons and the skeleton connectors are riveted and assembled to reduce the manufacturing difficulty; or the integral hollow skeleton structure is split into two "C" -shaped structures and then adhesively assembled to reduce the manufacturing difficulty.

[0004] Dividing the tandem skeleton structure into at least five parts such as front / rear skeletons, upper connectors, inner / outer connectors, and intermediate connectors, connection areas need to be designed and strengthened for these five parts, and rivets are used to rivet and assemble the five parts, resulting in a large sacrifice of product weight; for the riveting and assembly of five products, assembly tooling needs to be manufactured for assembly positioning, and the requirement for assembly tooling is higher; the rigidity of a single part becomes weaker, the part deformation becomes larger, and the assembly difficulty is greater.

[0005] Splitting the integral hollow skeleton structure into two "C" -shaped structures and then adhesively assembling them requires designing connection areas and strengthening the connection areas, resulting in a large sacrifice of product weight; for the assembly of two products, assembly tooling needs to be manufactured for assembly positioning, and the requirement for assembly tooling is higher; the rigidity of a single part becomes weaker, the part deformation becomes larger, the assembly difficulty is greater, and the final external shape accuracy of the product is lower.

[0006] Therefore, currently, it is required that the integral hollow skeleton structure cannot be split and must be processed integrally, so new process methods are needed. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a forming method for an integral tandem composite hollow skeleton, which can improve the forming quality of the integral tandem composite hollow skeleton and reduce the manufacturing cost.

[0008] The technical solution of the present invention is as follows:

[0009] A method for molding an integral tandem composite hollow skeleton includes the following steps:

[0010] S1, mold design and manufacturing;

[0011] S2, Prototype Design and Manufacturing;

[0012] S3, using molds and prototypes to manufacture airbags;

[0013] S4, lay up the composite material fabric layer in the mold;

[0014] S5, Place the airbag in the laid-up composite fabric layer;

[0015] S6, perform composite material fabric layer back wrapping, wrapping the airbag with composite material fabric layer back wrapping;

[0016] S7, perform pre-molding and final mold closing;

[0017] S8 provides a vacuum environment and a thermosetting environment for the mold after it is closed;

[0018] S9, open the mold, first remove the airbag, then remove the product;

[0019] The airbag is a silicone capsule made of silicone, and the silicone capsule contains a support column.

[0020] Furthermore, the airbags in the S3 are manufactured using uncured silicone sheets or raw silicone sheets, with a total thickness of 4.5-6mm.

[0021] Furthermore, the steps in S3 include:

[0022] S31, Place the sample in the lower mold of the mold;

[0023] S32, apply silicone sheets layer by layer on the sample, and vacuum each layer of silicone sheet is applied; when applying, leave an air inlet for the airbag;

[0024] S33, add support columns in the weak rigidity area, the support columns are columns formed by rolling up silicone sheets.

[0025] Furthermore, in S33, the lower side of the support column is connected to the laid silicone sheet, and the upper side of the support column is isolated from the silicone sheet laid on the upper side by a separator.

[0026] Furthermore, the airbag is an airbag with a break, specifically: in the airbag manufacturing step S32, a break is reserved where the silicone sheet is not connected, and the break is located at the outermost boundary position of the corresponding composite hollow skeleton; the unconnected breaks are separated by a partition plate after demolding.

[0027] Furthermore, in S5, when using an airbag with a break, pressure equalization treatment is performed at the break point:

[0028] Use an isolation membrane to cover the break in the airbag; place an uncured silicone sheet in the middle gap at the break and cover it with an isolation membrane; finally, place a local pressure equalization plate at the break.

[0029] Furthermore, in S4, after the composite material fabric layer is laid, a layer of polyvinyl fluoride film is laid to isolate it from the airbag; in S5, talc powder is applied between the airbag and the polyvinyl fluoride film.

[0030] Furthermore, in S6, the overlap positions of each back-wrap fabric layer are staggered to avoid excessive thickness in some areas; the overlap size is 15-25mm.

[0031] Furthermore, this also includes the manufacture and use of prefabricated sheets:

[0032] Manufacturing preforms: Preforms are manufactured using materials of the same system as the hollow skeleton of the composite material, and the number of layers in the preforms is 1 to 2.

[0033] Using preforms: In the S7 mold closing process, the preforms are placed in the mold closing position and remain on the surface of the composite hollow skeleton after molding.

[0034] The beneficial effects of this invention are as follows:

[0035] (1) The silicon capsule of the present invention serves as both a layup mold and a pressure transmission medium, which facilitates the product layup process, simplifies the operation process, and improves operability.

[0036] (2) The silicon capsule of this invention has ductility in its radius (R-angle), allowing for compaction and equalization of the product's radius during the curing process, resulting in a higher quality radius than that achieved using the vacuum bag method;

[0037] (3) The curing pressure of the composite material of the present invention is positive pressure of the autoclave, which has low requirements for the overall rigidity of the tooling structure. The tooling structure can be designed as a simple, lightweight thin-shell tooling.

[0038] (4) When designing the size of the silicon capsule in this invention, a compensation gap is left between the silicon capsule and the inner surface of the product. At the same time, the thin-shell structure tooling is easy to operate and does not produce fabric clamping defects.

[0039] (5) The present invention adds a support structure to the airbag. The support structure is connected to one side of the airbag and separated from the other side of the airbag. This structure can enhance the rigidity of the silicone capsule and realize the function of the silicone capsule as a laying mold in the product laying process.

[0040] (6) The airbag structure with a break proposed in this invention can realize the deployment of the tandem airbags after the product is manufactured, which can achieve the effects of reuse and cost reduction.

[0041] (7) The silicon capsule of the present invention does not require filling with sand, is lightweight, and can realize the manufacture and use of large-size silicon capsules. The design can realize the manufacture of large-scale tandem composite hollow skeleton products. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this invention, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 The attached figure shows the integral tandem composite hollow skeleton structure processed according to the present invention;

[0044] Figure 2 The attached figure shows the integral tandem silicon capsule structure with fracture of the present invention;

[0045] Figure 3 The attached figure shows the splicing structure of two separately enclosed silicon capsules in an embodiment of the present invention;

[0046] Figure 4 The accompanying drawings show the structure of the silicon capsule with added support and local thickening in an embodiment of the present invention;

[0047] Figure 5 The attached figure shows the method for manufacturing the fracture surface of the silicon capsule in an embodiment of the present invention;

[0048] Figure 6 The attached figure shows the method for splicing the fracture surface of the silicon capsule and equalizing the pressure of the present invention.

[0049] Among them, 1—isolation membrane or Tedra film, 2—array-type support column structure, 3—conventional raw silicone sheet layup, 4—re-wrapping raw silicone sheet layup at the break, 5—release cloth, 6—isolation plate, 7—break splicing structure silicone capsule 1, 8—break splicing structure silicone capsule 2, 9—Tedra film, 10—splitting silicone (silicone or raw silicone sheet) filling at the splice, 11—pressure equalization pad. Detailed Implementation

[0050] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0051] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are given in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integrated connection; they can refer to a mechanical connection or a point connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] Example 1:

[0054] A method for molding an integral tandem composite hollow skeleton includes the following steps:

[0055] S1, mold design and manufacturing;

[0056] S2, Prototype Design and Manufacturing;

[0057] S3, using molds and prototypes to manufacture airbags;

[0058] S4, lay up the composite material fabric layer in the mold;

[0059] S5, Place the airbag in the laid-up composite fabric layer;

[0060] S6, perform composite material fabric layer back wrapping, wrapping the airbag with composite material fabric layer back wrapping;

[0061] S7, perform pre-molding and final mold closing;

[0062] S8 provides a vacuum environment and a thermosetting environment for the mold after it is closed;

[0063] S9, open the mold, first remove the airbag, then remove the product;

[0064] The airbag is a silicone capsule made of silicone, and the silicone capsule contains a support column.

[0065] The airbags in the S3 are manufactured by laying uncured silicone sheets or raw silicone sheets, with a total laying thickness of 4.5-6mm.

[0066] The steps in S3 include:

[0067] S31, Place the sample in the lower mold of the mold;

[0068] S32, apply silicone sheets layer by layer on the sample, and vacuum each layer of silicone sheet is applied; when applying, leave an air inlet for the airbag;

[0069] S33, add support columns in the weak rigidity area, the support columns are columns formed by rolling up silicone sheets.

[0070] In S33, the lower side of the support column is connected to the laid silicone sheet, and the upper side of the support column is isolated from the silicone sheet laid on the upper side by a separator.

[0071] The airbag is an airbag with a break. Specifically, in the manufacturing step S32 of the airbag, a break is reserved where the silicone sheet is not connected. The break is located at the outermost boundary of the corresponding composite hollow skeleton. The unconnected breaks are separated by a partition plate after demolding.

[0072] In S5, when using an airbag with a break, pressure equalization treatment is performed at the break point:

[0073] Use an isolation membrane to cover the break in the airbag; place an uncured silicone sheet in the middle gap at the break and cover it with an isolation membrane; finally, place a local pressure equalization plate at the break.

[0074] In S4, after the composite material fabric layer is laid, a layer of polyvinyl fluoride film is laid to isolate it from the airbag; in S5, talc powder is applied between the airbag and the polyvinyl fluoride film.

[0075] In S6, the overlap positions of each back-wrap fabric layer are staggered to avoid excessive thickness in some areas; the overlap size is 15-25mm.

[0076] This also includes manufacturing prefabricated sheets and using prefabricated sheets:

[0077] Manufacturing preforms: Preforms are manufactured using materials of the same system as the hollow skeleton of the composite material, and the number of layers in the preforms is 1 to 2.

[0078] Using preforms: In the S7 mold closing process, the preforms are placed in the mold closing position and remain on the surface of the composite hollow skeleton after molding.

[0079] Example 2:

[0080] The main technical concept adopted in this invention is as follows:

[0081] (1) In terms of molding principle, the principle of composite material “mother and daughter bag” is applied. The “daughter bag” material in the mother and daughter bag is upgraded from vacuum bag to silicone capsule. The sealing of “daughter bag” and “mother bag” is optimized so that “daughter bag” and “mother bag” are sealed with mold respectively. Among them, the silicone capsule of “daughter bag” is sealed with mold through a more suitable vent, and the “mother bag” is sealed with mold using putty strip.

[0082] (2) Silicon capsules with large cross-sectional areas enhance rigidity by increasing the thickness of the silicon capsule and adding local support structures, so that the silicon capsule can serve as both a placement mold in the product laying process and a pressure transmission medium in the curing process.

[0083] (3) Silicon capsules can be designed as an integral tandem structure;

[0084] (4) The overall serial structure can increase local cuts to enable the reusability of the silicone capsule;

[0085] (5) Silicon capsules can be designed as spliced ​​structures to enable reusability of silicon capsules.

[0086] (6) Based on the "mother and daughter bag" molding principle, the pressure of the inner bag and the outer bag is provided by the autoclave, the pressure is uniform, and the molding mold of the overall serial composite hollow skeleton is designed as a lightweight thin shell structure.

[0087] It should be noted that, in the implementation examples, those skilled in the art can exhaustively explore all possibilities based on mathematical knowledge of permutations and combinations. Therefore, this invention will not describe each technical solution after permutation and combination, but it should be understood that the technical solutions after permutation and combination have been disclosed by this invention. The above descriptions are merely preferred examples of this invention and are not intended to limit this invention. For those skilled in the art, this invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0088] (3) Specific implementation steps of the present invention

[0089] Step 1: Tooling Design;

[0090] For ease of operation, the tooling is designed with a lightweight, thin-shell structure. The following points should also be noted:

[0091] (a) Tooling is rationally divided into blocks;

[0092] (ii) The upper and lower parting surfaces should be located near the radius (R-angle);

[0093] (iii) Avoid closed angles;

[0094] (iv) Each side mold that needs to be disassembled shall be designed with an opening port or opening device;

[0095] (v) The plane is used as the upper mold surface, and the stepped surface is used as the lower mold surface;

[0096] (vi) The lifting points should be set according to the weight of the disassembled mold parts, and the lifting positions should be reasonable;

[0097] (vii) Perform stiffness simulation analysis;

[0098] (viii) A mold closing guide device is installed, and the mold closing guidance is reasonable;

[0099] (ix) It can achieve sealing, and a leak-proof block is designed on the back of the main mold assembly position;

[0100] (x) The air vent of the silicone capsule is matched with the opening of the mold body;

[0101] (xi) Tooling shall be made of Invar steel, or the thermal shrinkage ratio shall be taken into account.

[0102] Step 2: Tooling manufacturing;

[0103] After the tooling is manufactured, the following points should be noted:

[0104] (I) Inspecting the machining accuracy of tooling

[0105] (ii) Conduct an airtightness test

[0106] Step 3: Sample design (as needed; no sample is needed if there is a special molding mold for silicone capsules);

[0107] (i) The sample material may be a high-temperature resistant composite material or other high-temperature resistant material;

[0108] (ii) The sample thickness is designed to be 1.5 times the product thickness;

[0109] (iii) Calculate the number of layers based on the thickness of a single layer of material;

[0110] (iv) The layup is done by butt joints;

[0111] (v) Symmetrical ply design;

[0112] (vi) Manufactured using the vacuum bag-autoclave method;

[0113] (vii) Manufactured using molding dies;

[0114] (viii) The boundary between the sample and the mold is consistent.

[0115] Step 4: Sample manufacturing (as needed; no sample is needed if there is a special molding mold for silicone capsules);

[0116] (a) The sample layup process adopts a butt joint splicing method;

[0117] (ii) Select curing parameters that match the material

[0118] (iii) The sample is machined to be flush with or within 0.2mm below the mold parting surface of the tooling mold body;

[0119] (iv) Grind areas that are too thick and thicken areas that are too thin;

[0120] (v) Grind the R-angle until it matches the inner R-angle of the product;

[0121] (vi) The sample is divided into sections at parallel points to ensure no stress between it and the molding mold;

[0122] Step 5: Airbag Manufacturing

[0123] (a) Silicone capsules can be in three forms:

[0124] 1) Integral tandem silicone capsules;

[0125] To maintain consistency with the product, the entire tandem structure has a closed cross-section. Except for the air vent, where gas can flow, the entire tandem silicon capsule is a sealed structure. (See...) Figure 2 ;

[0126] 2) Silicone capsules with fractures;

[0127] Only one edge of the outermost closed structure remains continuous; all other closed structures have a break, and the break is closed. See [reference needed]. Figure 3 This allows the silicone capsules to be reused;

[0128] 3) Two silicone capsules are joined together;

[0129] Disconnect all enclosed structures and use two silicone capsules, each enclosed by a separate silicone seal, to join together. See [link / reference]. Figure 4 Silicon capsules can also be reused;

[0130] (ii) The silicone capsule material shall be 1453 uncured silicone sheet or other raw silicone sheet and other materials with similar properties;

[0131] (iii) The thickness of the raw silicone sheet should be 3 to 4 layers (1.5 mm per layer; for other thicknesses of silicone sheets, the number of layers needs to be converted) or silicone support points should be added to ensure a certain rigidity;

[0132] Special note: The thickness of the silicone sheet should be appropriate. When the product cavity size is ≤50mm, 3 layers of silicone sheets can be directly laid; when the product cavity size is >50mm, 4 layers of silicone sheets can be laid. See [link / reference]. Figure 5 The silicone thickness should not be too thick, as this is not conducive to pressure transmission during the curing process.

[0133] (iv) Vacuum-sealing is performed after each layer of silicone sheet is laid;

[0134] The vacuuming parameters are: vacuum -0.07MPa, time not less than 15min;

[0135] (V) In areas where rigidity remains relatively weak, add silicone support points. These support points should be prisms with a diameter of 10–20 mm or cuboids with a side length of 10–20 mm. Place a release diaphragm (or other material with good isolation effect) on the upper side of the support point to isolate it from the upper silicone capsule. The lower side of the support point should connect to the silicone capsule. See [link to relevant documentation]. Figure 5 ;

[0136] (vi) For silicone capsules with breaks and silicone capsules made by splicing two silicone capsules, a separator plate must be placed at the break. The separator plate should be approximately 0.5–1 mm thick and made of composite material or metal. The surface of the separator plate should be treated with a release agent (applied with a release agent, a release cloth, or a release film). Silicone sheets should be used to seal the end faces of the capsule on both sides of the separator plate. See [link to relevant documentation]. Figure 6 ;

[0137] (vii) The silicone capsule is a hollow capsule with local silicone support points, and does not need to be filled with sand or other materials;

[0138] Special note: Not filling with sand can effectively reduce the weight of the silicone capsule and enhance its ease of handling.

[0139] Step 6: Precast panel manufacturing (on demand)

[0140] (i) Use glass fiber prepreg with the same resin system as the product to manufacture preforms, with 1 to 2 layers and a thickness generally not exceeding 0.3 mm;

[0141] (ii) The preform is a pad for placing the mold clamping cloth at the tooling mold closing position after the product layup is completed. It can remain on the product surface after the product is formed. If a release film is added between the preform and the layup, the preform can be removed after the product is formed.

[0142] Step 7: Laying out layers

[0143] (i) The layers should be laid, pressed, and rolled firmly, without bridging or wrinkling; and spliced ​​as required; and a backing layer should be left, with proper separation between the backing layers;

[0144] (ii) Vacuum the first layer after laying, and vacuum every 3 to 4 subsequent layers;

[0145] (iii) After all the layers are laid before repackaging, a layer of polyvinyl fluoride film is laid to isolate it from the silicone capsule and facilitate demolding.

[0146] Step 7: Placement of the silicone capsule

[0147] (i) Place the silicon capsule in the layup, and place the air inlet in the opening that is coordinated with the tooling;

[0148] Special attention should be paid to checking the accuracy of the placement of the silicone capsules to ensure that there are no issues such as bridging or stress.

[0149] (ii) Apply talc powder between the silicone capsule and the polyvinyl fluoride film (such as CZ-PVF-25) (as needed); talc powder helps with demolding, but special care should be taken to protect the layup when applying talc powder to prevent talc powder from entering the prepreg.

[0150] (III) When using silicone capsules with breaks or silicone capsules joined together, due to the common dimensional shrinkage of silicone capsules, pressure equalization treatment must be performed at the silicone breaks or joints. The pressure equalization method is as follows:

[0151] Cover the cut with a polyvinyl fluoride film (or release cloth, release film); place an uncured silicone sheet (or silicone with similar properties to RTV1556 and other materials with similar properties) in the gap between the cut or splice and fill it with a polyvinyl fluoride film (or release cloth, release film).

[0152] Place a local pressure equalization plate (0.2mm to 0.3mm thick prepreg) at the joint;

[0153] Step 8: Fabric layer re-wrapping

[0154] (i) The overlapping positions of each back-wrap fabric layer are staggered to avoid excessive thickness in some areas;

[0155] (ii) The overlap size of the back wrap is 15-25mm;

[0156] (iii) Avoid over-tightening the back-wrapping fabric layer; over-tightening will cause greater resistance to the gradual sliding of the fabric layer during the curing process, and is prone to delamination and voids exceeding tolerance.

[0157] Step 9: Pre-molding

[0158] (i) Pre-close the mold, and use guide pins to ensure the accuracy of mold closing when closing the mold. The gap between mold closing and mold closing should be ≤0.2mm.

[0159] (ii) Pre-molding confirmation to ensure successful mold closing;

[0160] (iii) After pre-molding, open the mold again to treat the defective fabric layers;

[0161] Step 10: Place the precast sheet (as needed)

[0162] (i) The length of a single precast sheet should not be too long, ≤150mm, or a 1mm vent hole should be made; the width of a single side of the precast sheet should not be greater than 15mm;

[0163] (ii) Precast sections should be joined with a gap of 0-2mm; overlap is not allowed.

[0164] Step 11: Mold assembly

[0165] (a) Mold closing shall be carried out in accordance with the pre-mold closing method;

[0166] (ii) Control the mold closing gap to ≤0.2mm;

[0167] Step 12: Constructing Vacuum Bags

[0168] (i) Vacuum bags should not be bridged or sealed;

[0169] (ii) The number and location of vacuum nozzles meet the requirements for vacuuming and vacuum testing;

[0170] Step 13: Vacuum Degree Detection

[0171] After the vacuum bag is made, the vacuum level is checked.

[0172] Step 14: Curing

[0173] (a) Curing using an autoclave;

[0174] (ii) Determine the curing parameters according to the materials used;

[0175] Step 15: Unmolding

[0176] (a) Remove the tooling cover plate, side mold, etc. from the main mold body;

[0177] (ii) Remove the product from the main mold body;

[0178] (iii) Remove the silicone capsule from the product;

[0179] Special note: When using a single, unbroken silicone capsule, the capsule must be broken to remove it; when using a single, broken silicone capsule or a spliced ​​silicone capsule, the capsule can be removed gradually and is reusable.

[0180] Example 3:

[0181] constitute:

[0182] (I) Molding Principle

[0183] In terms of molding principle, the "mother-daughter bag" principle of composite materials is applied. The material of the "daughter bag" in the mother-daughter bag is upgraded from a vacuum bag to a silicone capsule. The sealing of the "daughter bag" and the "mother bag" is optimized so that the "daughter bag" and the "mother bag" are sealed with the mold respectively. The silicone capsule of the "daughter bag" is sealed with the mold through a more suitable vent, while the "mother bag" is sealed with the mold using putty strips.

[0184] (II) Tooling Structure

[0185] A thin-shell tooling is used, with air ports that match the overall tandem silicon capsule.

[0186] (III) Integral tandem silicone capsules

[0187] The silicon capsule is designed as an integral, serial structure and is a disposable silicon capsule.

[0188] (iv) Integral tandem silicone capsules with a break

[0189] The silicon capsule is designed as an integral serial structure with a break, which allows it to be reused.

[0190] (V) Tandem Silicon Capsules with Spliced ​​Structure

[0191] The silicone capsule is designed with a modular structure, which allows it to be reused.

[0192] (vi) Methods for Strengthening Silicon Capsule Structure

[0193] 1) Increase the thickness of the local silicone sheet layer;

[0194] 2) Apply slight positive pressure during layer layup.

[0195] (vii) Method for manufacturing the fracture surface of silicone capsules

[0196] Use a release liner to isolate the silicone capsules on both sides of the fracture; lay a re-wrapped raw silicone sheet at the fracture to ensure the silicone capsules are sealed at the fracture.

[0197] (viii) Methods for splicing silicone capsule fracture surfaces and applying pressure during product manufacturing

[0198] Cover the cut with a polyvinyl fluoride film (or release cloth, release film); place an uncured silicone sheet (or silicone with similar properties to RTV1556 and other materials with similar properties) in the gap between the cut or splice and fill it with a polyvinyl fluoride film (or release cloth, release film).

[0199] Place a local pressure equalization plate (0.2mm to 0.3mm thick prepreg) at the joint.

[0200] (ix) Apply talc powder between the silicone capsule and the polyvinyl fluoride film (such as CZ-PVF-25);

[0201] Talc powder helps with demolding, but special care must be taken to protect the layup when brushing on the talc powder to prevent it from getting into the prepreg.

[0202] Implementation steps:

[0203] Step 1: Tooling Design;

[0204] For ease of operation, the tooling is designed with a lightweight, thin-shell structure.

[0205] Step 2: Tooling manufacturing;

[0206] After the tooling is manufactured, attention should be paid to checking the machining accuracy of the tooling and performing an airtightness check. Third step: Sample design (as needed; no sample is needed if a special molding die for silicone capsules is available);

[0207] Step 4: Sample manufacturing (as needed; no sample is needed if there is a special molding mold for silicone capsules);

[0208] Step 5: Airbag Manufacturing

[0209] Silicon capsules can come in three forms: integral tandem silicone capsules; silicone capsules with a break; and two silicone capsules joined together.

[0210] Step 6: Precast panel manufacturing (on demand)

[0211] Step 7: Laying out layers

[0212] The layers should be laid out, pressed firmly, and rolled out smoothly, without bridging or wrinkling; and spliced ​​according to requirements; leaving a backing layer, and ensuring proper separation between the backing layers;

[0213] Step 7: Placement of the silicone capsule

[0214] Place the silicon capsule in the layup, and position the air inlet in the opening that is coordinated with the tooling;

[0215] Step 8: Fabric layer re-wrapping

[0216] The overlap positions of each back-wrap fabric layer should be staggered to avoid excessive thickness in some areas; the overlap size should be 15-25mm; the back-wrap fabric layer should not be too tight; if it is too tight, it will cause greater resistance to the gradual sliding of the fabric layer during the curing process, and is prone to delamination and gap exceeding tolerance.

[0217] Step 9: Pre-molding

[0218] Pre-assemble the mold, and use guide pins to ensure the accuracy of mold closing during mold closing. The gap between mold closing and mold closing should be ≤0.2mm.

[0219] Step 10: Place the precast sheet (as needed)

[0220] Step 11: Mold assembly

[0221] Control the mold closing gap to ≤0.2mm;

[0222] Step 12: Constructing Vacuum Bags

[0223] Step 13: Vacuum Degree Detection

[0224] After the vacuum bag is made, the vacuum level is checked.

[0225] Step 14: Curing

[0226] Curing is performed using an autoclave;

[0227] Step 15: Unmolding

[0228] Remove the tooling cover plate, side mold, etc. from the main mold body; remove the product from the main mold body; remove the silicone capsule from the product.

Claims

1. A method for molding an integral tandem composite hollow skeleton, characterized in that, Includes the following steps: S1, mold design and manufacturing; S2, Prototype Design and Manufacturing; S3, using molds and prototypes to manufacture airbags; S4, lay up the composite material fabric layer in the mold; S5, Place the airbag in the laid-up composite fabric layer; S6, perform composite material fabric layer back wrapping, wrapping the airbag with composite material fabric layer back wrapping; S7, perform pre-molding and final mold closing; S8 provides a vacuum environment and a thermosetting environment for the mold after it is closed; S9, open the mold, first remove the airbag, then remove the product; The airbag is a silicone capsule made of silicone, and the silicone capsule contains a support column; The airbags in the S3 are manufactured by laying uncured silicone sheets or raw silicone sheets, with a total laying thickness of 4.5-6mm; The steps in S3 include: S31, Place the sample in the lower mold of the mold; S32, apply silicone sheets layer by layer on the sample, and vacuum each layer of silicone sheet is applied; when applying, leave an air inlet for the airbag; S33, adding support columns in the weak rigidity area, the support columns are columns formed by rolling up silicone sheets; The airbag is an airbag with a break. Specifically, in the manufacturing step S32 of the airbag, a break is reserved where the silicone sheet is not connected. The break is located at the outermost boundary of the corresponding composite hollow skeleton. The unconnected breaks are separated by a partition plate after demolding.

2. The method for forming an integral tandem composite hollow skeleton according to claim 1, characterized in that, In S33, the lower side of the support column is connected to the laid silicone sheet, and the upper side of the support column is isolated from the silicone sheet laid on the upper side by a separator.

3. The method for forming an integral tandem composite hollow skeleton according to claim 1, characterized in that, In S5, when using an airbag with a break, pressure equalization treatment is performed at the break point: Use an isolation membrane to cover the break in the airbag; place an uncured silicone sheet in the middle gap at the break and cover it with an isolation membrane; finally, place a local pressure equalization plate at the break.

4. The method for forming an integral tandem composite hollow skeleton according to claim 1, characterized in that, In S4, after the composite material fabric layer is laid, a layer of polyvinyl fluoride film is laid to isolate it from the airbag; in S5, talc powder is applied between the airbag and the polyvinyl fluoride film.

5. The method for forming an integral tandem composite hollow skeleton according to claim 1, characterized in that, In S6, the overlap positions of each back-wrap fabric layer are staggered to avoid excessive thickness in some areas; the overlap size is 15~25mm.

6. The method for forming an integral tandem composite hollow skeleton according to claim 1, characterized in that, This also includes manufacturing prefabricated sheets and using prefabricated sheets: Manufacturing preforms: Preforms are manufactured using materials of the same system as the hollow skeleton of the composite material, and the number of layers in the preforms is 1 to 2. Using preforms: In the S7 mold closing process, the preforms are placed in the mold closing position and remain on the surface of the composite hollow skeleton after molding.

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