Method for rapidly preparing C-shaped section bistable composite material cylindrical shell structure based on thermoplastic preformed body and forming mold

Abstract

The invention discloses a method for rapidly preparing a C-shaped section bistable composite material cylindrical shell structure based on a thermoplastic preform and a forming mold, and designs a set of forming mold with low-temperature supporting property and high-temperature preforming function at the same time, and a flat plate structure with a heating function can support a thermoplastic preform sheet at low temperature; meanwhile, after being heated and softened at high temperature, the C-shaped composite bistable pipe can be quickly attached to the inner surface of the semicircular groove of the female die, and then the cylindrical male die is used for achieving winding forming of the C-shaped composite bistable pipe. A thermoplastic composite material prefabricated body is used, and integrated forming can be achieved in a designed mold tool. Compared with an existing conventional closed structure, rigid thermoplastic prefabricated body sheets can be used, cloth does not need to be laid layer by layer, continuous processing operation can be achieved, the forming period generally needing 1-2 h is shortened to 15 min for each piece, efficiency is greatly improved, and cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of preparation of a C-section bistable composite material column shell structure, and in particular relates to a method for rapidly preparing a C-section bistable composite material column shell structure based on a thermoplastic preform and a forming die. Background Art

[0002] The bi-directionally curlable and stable composite material bistable shell structure with a C-shaped cross section is a bi-directionally curlable and stable composite material shell structure. There are two ways to realize the bistable structure: one is to use shell structures with different bending directions to stack layer by layer to form an integral shell structure, and the shell structures with different bending directions can affect the composite shell structure in their respective directions; the second method mainly uses the anisotropy of the composite material, first pre-formed composite column structure, when subjected to external forces in directions different from the pre-formed bending direction, strain energy is formed, and finally the second stable state is reached. For this reason, the composite material bistable column shell structure has received attention at home and abroad, and a series of derivative products have been developed, which can realize various support functions, while also ensuring low weight and rapid deployment. In 2000, Iqbal K, Daton-Lovett and others published an article on bistable tubes made of composite materials, and applied for patents such as US6217975 and US6256938 in 2001.

[0003] Patent No. US6217975B1 introduces an extensible hollow tube structure using reinforced fiber fabric and resin composite, and explains that the invention uses the characteristics of the composite fiber layer to give the invention a bistable characteristic, which can be curled in both directions. The appearance of the inventive structure is shown in Figure 5. Direction A is the state of the length direction, at which time a tubular structure with an opening can be formed, and direction B is a completely curled state, which can form a tubular structure wrapped layer by layer. When in state A, a pressure can be applied to direction A from the outside to make the structure transform into state B; in state B, a tension can be applied to direction A from the outside to make the structure transform into state A. However, this manufacturing method is affected by the length of the substrate layer and / or the fiber layer. The length of the bistable column shell structure that can be manufactured is actually preset, which is the same as the length of the substrate layer and / or the fiber layer, and a bistable shell structure with unlimited length cannot be continuously manufactured. Moreover, the strength of the bistable column shell structure manufactured by this manufacturing method is not good. When the length exceeds 10 meters, the bistable column shell structure can no longer be used as a C-shaped tube.

[0004] The China Aerospace Special Materials and Process Technology Research Institute also applied for patents 201810259481.6 and 201810174454.9, and reported a box-type molding mold in the 201810174454.9 patent. However, the mold still has the disadvantages of low molding efficiency and is not suitable for the rapid prototyping process of preforms. Therefore, it is urgent to provide a method for mass production of a composite bi-stable cylindrical shell structure with a C-shaped cross-section that can be curled and stabilized in both directions. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method and a forming mold for rapidly preparing a C-section bistable composite material column shell structure based on a thermoplastic preform.

[0006] A forming mold for a bistable composite column shell structure with a C-shaped cross-section is quickly prepared based on a thermoplastic preform, comprising a lower female mold and an upper male mold, wherein the middle portion of the lower female mold is recessed downward to form a semicircular cylindrical forming groove, and support platforms are formed on the left and right sides of the semicircular cylindrical forming groove; the upper male mold comprises two semi-cylindrical hollow shells hinged at the lower ends, and the two semi-cylindrical hollow shells can form a complete hollow cylinder when closed, the outer diameter of the upper male mold is smaller than the inner diameter of the semi-circular cylindrical forming groove, and the difference is .-mm, the upper surface of the lower female mold is used to place the thermoplastic preform, and a heating plate is arranged inside the lower female mold, and the heating plate is used to heat the thermoplastic preform.

[0007] Furthermore, the inner diameter of the semicircular columnar forming groove is larger than the diameter of the target C-section composite material bistable columnar structure.

[0008] Furthermore, the upper male mold also has a heating function for heating the outer thermoplastic preform.

[0009] A method for rapidly preparing a C-shaped cross-section bistable composite column shell structure based on a thermoplastic preform comprises the following steps:

[0010] Step 1, the raw material adopts a thermoplastic preform, the thermoplastic preform is a plastic sheet with a thickness of .-mm or a curved plastic sheet with a curvature K satisfying ≤K≤ / R, the thermoplastic preform is placed on the upper surface of the semicircular columnar molding groove of the lower female mold, and the thermoplastic preform is heated by the lower female mold until the thermoplastic preform is softened;

[0011] Step 2, after closing the upper male mold into a cylinder, the upper male mold is inserted into the semicircular columnar molding groove and pressed onto the upper surface of the thermoplastic preform, the upper male mold is pressurized and shaken left and right at the same time, so that the upper male mold extrude and shape the thermoplastic preform for multiple times until the thermoplastic preform is completely covered on the outer side of the upper male mold and forms a C-shaped structure;

[0012] Step 3: Take out the upper male mold from the semicircular columnar forming groove, open the upper male mold for demoulding, and obtain a C-section bistable composite material column shell structure.

[0013] Furthermore, the resin matrix of the thermoplastic preform is pure plastic or modified plastic.

[0014] The present invention has the following beneficial technical effects:

[0015] The present invention designs a set of forming molds that have both low-temperature support and high-temperature preforming functions. Its heated flat plate structure can support thermoplastic preform sheets at low temperatures, and can be quickly attached to the inner surface of the semicircular groove of the female mold after being softened by high-temperature heating. Then, a cylindrical male mold is used to realize the winding forming of the C-type composite material bistable tube. Using thermoplastic composite preforms, it can be integrated into the designed mold tooling. Compared with the existing conventional closed structure, rigid thermoplastic preform sheets can be used, and there is no need to lay them layer by layer, which can realize continuous processing operations, shortening the molding cycle that generally takes 1-2 hours to 15 minutes per piece, greatly improving efficiency and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a three-dimensional schematic diagram of the mold of the present invention;

[0017] Figure 2 This is a schematic diagram of the mold when the upper positive mold is placed in the upper negative mold for processing;

[0018] Figure 3 Schematic diagram of the mold when the upper positive mold is removed from the upper negative mold and prepared for demoulding.

[0019] The components represented by the reference numerals in the accompanying drawings are as follows:

[0020] 1. Lower female mold; 2. Upper male mold; 3. Semicircular columnar molding groove; 4. Support platform; 5. Thermoplastic preform DETAILED DESCRIPTION

[0021] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] like Figure 1-3As shown, a forming mold for quickly preparing a C-section bistable composite material column shell structure based on a thermoplastic preform is characterized in that it includes a lower female mold 001 and an upper male mold 002, the middle part of the lower female mold is recessed downward to form a semicircular cylindrical forming groove 003, and the left and right sides of the semicircular cylindrical forming groove 003 form a supporting platform 004; the upper male mold 002 includes two semi-cylindrical hollow shells hinged at the lower ends, and the two semi-cylindrical hollow shells can form a complete hollow cylinder after closing, the outer diameter of the upper male mold 002 is smaller than the inner diameter of the semi-circular cylindrical forming groove 003, and the difference is 0.5-3mm, the upper surface of the lower female mold 001 is used to place the thermoplastic preform 005, and a heating plate is arranged inside the lower female mold 001, and the heating plate is used to heat the thermoplastic preform 005.

[0023] Example 1

[0024] Glass fiber / PP laminate is used as the preform material of the C-shaped bistable column shell structure. First, fix the two ends of any long side of the PP / GF laminate on the limit clamps of the molding mold to prevent the preform from twisting and deformation due to torsion during molding. Secondly, heat the lower female mold 001 of the mold to the melting temperature of PP plastic, generally 190-210℃, and after softening for 5-20 minutes, install the male mold 002 into the semicircular groove 003 of the female mold. The female mold is tightened from both ends to the middle by bite-type mold clamping. At this time, the softened preform is gradually fitted with the middle male mold under the bending of the left and right petal molds of the female mold. The final mold clamping pressure is controlled at 1-5bar by an air compressor, maintained for 30 seconds, and then the pressure is released to the initial pressure, and then pressurized to 1-5bar. After repeating the above pressurization process 2-5 times, the pressure is maintained at 1-bar and the temperature is maintained at 190-210°C. After maintaining for 5 minutes, the temperature is lowered to below 80°C and demoulding is performed to obtain a C-shaped cross-section bistable composite column shell structure. A vertical external force is applied to one end of the C-shaped opening of the columnar structure to open it and gradually roll it up, and a stable rolled-up C-shaped bistable shell structure can be obtained.

[0025] Example 2

[0026] Glass fiber / PA6 laminate is used as the preform material of the C-shaped bistable column shell structure. First, fix the two ends of any long side of the PP / GF laminate on the limit clamps of the molding mold to prevent the preform from twisting and deformation due to torsion during molding. Secondly, heat the lower female mold 001 of the mold to the melting temperature of PP plastic, generally 230-250℃, and after softening for 5-20 minutes, install the male mold 002 into the semicircular groove 003 of the female mold. The female mold is tightened from both ends to the middle by bite-type clamping. At this time, the softened preform is gradually fitted with the middle male mold under the bending of the left and right petal molds of the female mold. The final clamping pressure is controlled at 1-5bar by an air compressor, maintained for 30 seconds, and then the pressure is released to the initial pressure, and then pressurized to 1-5bar. After repeating the above pressurization process 2-5 times, the pressure is maintained at 1 bar and the temperature is maintained at 230-250°C. After maintaining for 5 minutes, the temperature is lowered to below 80°C and demoulded to obtain a C-shaped cross-section bistable composite column shell structure. A vertical external force is applied to one end of the C-shaped opening of the columnar structure to open it and gradually roll it up, and a stable rolled-up C-shaped bistable shell structure can be obtained.

[0027] The above is an example of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is also within the protection scope of the present invention.

Claims

1. A forming die for rapidly preparing a C-shaped cross-section bistable composite cylindrical shell structure based on a thermoplastic preform, characterized in that: The invention comprises a lower female mold (001) and an upper male mold (002), wherein the middle part of the lower female mold is concave downward to form a semicircular columnar molding groove (003), and the left and right sides of the semicircular columnar molding groove (003) form a supporting platform (004); the upper male mold (002) comprises two semi-cylindrical hollow shells hinged at the lower ends, and the two semi-cylindrical hollow shells can form a complete hollow cylinder after closing, the outer diameter of the upper male mold (002) is smaller than the inner diameter of the semi-circular columnar molding groove (003), and the difference is 0.5-3mm, the upper surface of the lower female mold (001) is used to place a thermoplastic preform (005), and a heating plate is arranged inside the lower female mold (001), and the heating plate is used to heat the thermoplastic preform (005).

2. A forming die for rapidly preparing a C-section bistable composite cylindrical shell structure based on a thermoplastic preform, characterized in that: The inner diameter of the semicircular columnar forming groove (003) is larger than the diameter of the target C-shaped cross-section composite material bistable columnar structure.

3. A forming die for rapidly preparing a C-shaped cross-section bistable composite cylindrical shell structure based on a thermoplastic preform, characterized in that: The upper male mold (002) also has a heating function, which is used to heat the outer thermoplastic preform (005).

4. A method for rapidly preparing a C-shaped cross-section bistable composite column shell structure based on a thermoplastic preform, characterized in that: The following steps are involved: Step 1: The raw material is a thermoplastic preform (005), wherein the thermoplastic preform (005) is a plastic sheet with a thickness of 0.5-3 mm or a curved plastic sheet with a curvature K satisfying 0≤K≤1 / R. The thermoplastic preform (005) is placed on the upper surface of the semicircular columnar molding groove (003) of the lower female mold (001), and the thermoplastic preform (005) is heated by the lower female mold (001) until the thermoplastic preform (005) softens. Step 2, the upper male mold (002) is closed to form a cylinder, and then embedded into the semicircular columnar molding groove (003) and pressed onto the upper surface of the thermoplastic preform (005), and the upper male mold (002) is pressurized and shaken left and right at the same time, so that the upper male mold (002) extrude and shape the thermoplastic preform (005) for multiple times until the thermoplastic preform (005) is completely covered on the outer side of the upper male mold (002) and forms a C-shaped structure; Step 3: Take the upper male mold (002) out of the semicircular columnar forming groove (003), open the upper male mold (002) for demoulding, and obtain a C-shaped cross-section bistable composite material column shell structure.

5. The method for rapidly preparing a C-shaped cross-section bistable composite column shell structure based on a thermoplastic preform according to claim 1, characterized in that: The resin matrix of the thermoplastic preform (005) is pure plastic or modified plastic.

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