Amphibious aircraft float, stamping die and manufacturing method

Abstract

The application relates to an amphibious aircraft float, a stamping die and a manufacturing method. The amphibious aircraft float is in the shape of a hull and is hot-stamped from a thermoplastic composite material composed of a thermoplastic resin and reinforcing fibers. The stamping die comprises an upper die, a lower die, a positioning device and a blank clamping device, the opposite surfaces of the upper die and the lower die are provided with male and female structures which are complementary to each other, the positioning device is fixed on the lower die, and the blank clamping device is used for clamping a blank to be stamped and is positioned by the positioning device so that the blank is positioned and supported directly above the female structure. The manufacturing method comprises the following steps: providing a stamping die, preparing a blank, heating the blank, hot-stamping and edge trimming. The amphibious aircraft float has the advantages of high strength, fatigue resistance, impact resistance and damage tolerance.

Description

Technical Field

[0001] This invention belongs to the field of amphibious aircraft, specifically relating to an amphibious aircraft float, a stamping die, and a manufacturing method. Background Technology

[0002] The unique amphibious takeoff and landing characteristics of amphibious aircraft give them advantages in multiple civilian and military applications. The main function of the floats on amphibious aircraft is to ensure the stability of the aircraft during takeoff and landing on water, equivalent to the landing gear of land-based aircraft. Currently, most amphibious aircraft float structures are made of carbon fiber reinforced thermosetting composite materials using RTM technology, which has problems such as low impact resistance and insufficient toughness. Summary of the Invention

[0003] The purpose of this invention is to provide an amphibious aircraft float, a stamping die, and a manufacturing method to solve the aforementioned problems. Therefore, the technical solution adopted by this invention is as follows:

[0004] According to one aspect of the present invention, an amphibious aircraft float is provided, wherein the amphibious aircraft float is hull-shaped and hot-stamped from a thermoplastic composite material, the thermoplastic composite material comprising thermoplastic resin and reinforcing fibers.

[0005] In a preferred embodiment, the reinforcing fiber may include glass fiber, carbon fiber, or polyimide fiber, etc., and the thermoplastic resin may include polypropylene, polyetheretherketone, polyaryletherketone, polyetherketoneketone, polyphenylene sulfide, polyetherimide, or polyphenylene sulfone, etc.

[0006] According to another aspect of the present invention, a stamping die for an amphibious aircraft float is also provided, wherein the amphibious aircraft float is as described above, the stamping die includes an upper die, a lower die, a positioning device, and a blank clamping device, the opposing surfaces of the upper die and the lower die have complementary male and female die structures, the positioning device is fixed on the lower die, and the blank clamping device is used to clamp the blank to be stamped and positioned by the positioning device, such that the blank is positioned and supported directly above the female die structure.

[0007] In a preferred embodiment, the upper die is provided with a positioning protrusion on each side of the male die structure, and the lower die is provided with a positioning groove on each side of the female die structure. The positioning groove cooperates with the positioning protrusion to limit the stamping stroke of the upper die.

[0008] In a preferred embodiment, both the upper mold and the lower mold are polished, and their surface finish is not less than level 10.

[0009] In a preferred embodiment, the positioning device includes a first positioning bracket, a second positioning bracket, and a third positioning bracket arranged in a "T" shape. The first positioning bracket and the second positioning bracket are connected by a connecting plate, which is fixedly connected to one end of the lower mold, and the third positioning bracket is fixedly connected to the other end of the lower mold.

[0010] In a preferred embodiment, the first positioning bracket, the second positioning bracket, and the third positioning bracket are all L-shaped and equipped with height-adjustable support members.

[0011] In a preferred embodiment, the blank clamping device includes a rectangular frame, four springs and four clamps, wherein one end of each spring is position-adjustably mounted on the rectangular frame and the other end is fixed to the clamp.

[0012] According to another aspect of the present invention, a method for manufacturing an amphibious aircraft float is provided, wherein the amphibious aircraft float is as described above, and the manufacturing method includes the following steps:

[0013] S1: Provide the stamping die as described above;

[0014] S2: Preparation of blanks: The thermoplastic composite material is processed into blanks to be stamped according to certain dimensions;

[0015] S3: Heating of the billet: The billet is fixed by the billet clamping device and then placed into the heating equipment for heating.

[0016] S4: Hot stamping, the blank taken from the heating equipment is quickly transferred to the preheated stamping die for stamping. After stamping, it is kept warm and pressured for a period of time before being taken out to obtain the float blank.

[0017] S5: Edge trimming: The float material is trimmed according to the designed dimensions to obtain the float.

[0018] In a preferred embodiment, in S3, the heating temperature of the blank is 50-100°C higher than the resin melting temperature, preferably 100°C, and the heating time is 3-10 min, preferably 5 min; in S4, the stamping speed is 50-100 mm / min, the stamping pressure is 1-5 MPa, the mold temperature is more than 10°C lower than the glass transition temperature of the resin matrix, and the holding time is not less than 1 min, preferably 3 min.

[0019] Compared to thermosetting composite material float structures, float structures made of thermoplastic composite materials have the following advantages:

[0020] 1. It has good toughness and superior impact resistance and fatigue resistance.

[0021] 2. Float structural components need to be connected to other parts. Drilling holes will increase the risk of defects. Float structural components made of thermoplastic composite materials can be welded to reduce assembly steps.

[0022] 3. The rapid stamping manufacturing process greatly shortens the manufacturing time, improves manufacturing efficiency, and enables rapid mass production. Attached Figure Description

[0023] Figure 1 This is a three-dimensional schematic diagram of the stamping mold for the floats of an amphibious aircraft according to an embodiment of the present invention;

[0024] Figure 2 yes Figure 1 A three-dimensional view of the upper die of the stamping mold for the floats of an amphibious aircraft.

[0025] Figure 3 yes Figure 1 A perspective view of the lower die of the stamping mold for the floats of an amphibious aircraft.

[0026] Figure 4 yes Figure 1 A perspective view of the blank clamping device of the stamping die for the amphibious aircraft floats;

[0027] Figure 5 yes Figure 1 A perspective view of the positioning device for the stamping die of the amphibious aircraft float;

[0028] Figure 6 yes Figure 1 The figure shows an assembly perspective view of the lower die of the stamping mold and the positioning device for the floats of an amphibious aircraft.

[0029] Figure 7 This is a flowchart of the manufacturing method of the amphibious aircraft float of the present invention;

[0030] Figure 8 This is an ultrasonic scanning curve of the internal quality test of the amphibious aircraft float of the present invention. Detailed Implementation

[0031] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative of the essential spirit of the technical solution of the present invention.

[0032] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0033] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0034] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0035] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0036] In the following description, in order to clearly demonstrate the structure and working method of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0037] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] like Figure 1-6 As shown, a stamping die for an amphibious aircraft float according to the present invention may include an upper die 1, a lower die 2, a positioning device 3, and a blank clamping device 4. The opposing surfaces of the upper die 1 and the lower die 2 have complementary male die structures 11 and female die structures 21. That is, the lower surface of the upper die 1 has a hull-shaped protrusion, and the upper surface of the lower die 2 has a hull-shaped cavity complementary to the hull-shaped protrusion. The shape and size of the hull-shaped cavity are consistent with the shape and size of the amphibious aircraft float. The upper die 1 and the lower die 2 are respectively fixed to the punch and platform of a hot press. Specifically, three screw holes 12 and 22 are respectively provided on both sides of the upper die 1 and the lower die 2 to facilitate fixing to the hot press with bolts. The hot press is commercially available, and its structure is well known, and will not be described in detail here. The positioning device 3 is fixed to the lower die 2, for example, by screws. The blank clamping device 4 is used to clamp the blank 100 to be stamped and positioned by the positioning device 3, so that the blank 100 is positioned and supported directly above the female mold structure 21 of the lower mold 2, thereby ensuring the stamping quality.

[0040] This stamping die has a reasonable structural design, high precision, high durability, and saves costs. It is suitable for stamping and molding of thermoplastic composite materials to manufacture structural parts with large curvature radii (i.e., amphibious aircraft floats). The resulting amphibious aircraft floats have advantages such as high strength, fatigue resistance, impact resistance, and damage tolerance.

[0041] The upper die 1 and lower die 2 are typically made of high-strength metal materials, such as stainless steel or aluminum, to improve their service life. Preferably, the upper die 1 and lower die 2 are polished, with a surface finish of not less than grade 10, i.e., surface roughness Ra ≤ 0.2 μm, tested according to standard GB / T 1031-2016. This ensures that the stamped product has a smooth and flat surface.

[0042] like Figure 2 and 3 As shown, the upper die 1 has a positioning protrusion 13 on each side (e.g., along the length) of the male die structure 11, and the lower die 2 has a positioning groove 23 on each side (e.g., along the length) of the female die structure 21. The positioning groove 23 cooperates with the positioning protrusion 13 to limit the stamping stroke of the upper die 1. The depth of the positioning groove 23 and the positioning protrusion 13 is substantially the same as the thickness of the amphibious aircraft float. In this embodiment, the positioning protrusion 13 is cuboid in shape. It should be understood that the positioning protrusion 13 is not limited to the shape shown; for example, it can be cylindrical.

[0043] like Figure 4As shown, the blank clamping device 4 includes a rectangular frame 41, four springs 42, and four clamps 43. The rectangular frame 41 is composed of four metal strips connected together, for example, by screws, welding, or riveting. One end of each spring 42 is adjustablely mounted on the rectangular frame 41, and the other end is fixed to a clamp 43. Specifically, a pair of opposing metal strips of the rectangular frame 41 are machined with mounting grooves 411 extending along the length direction, and one end of each spring 42 is mounted on the mounting groove 411 by screws. When the specifications of the blank to be stamped change, the mounting position of the springs 42 can be adjusted to adapt, which is very convenient. The springs 42 have a certain rigidity to keep the blank 100 horizontal before stamping. After stamping, the restoring force of the springs 42 can disengage the float blank from the lower die 2. The clamps 43 are metal clamps with a certain clamping force to ensure that the blank 100 will not be released during the stamping process.

[0044] Furthermore, such as Figure 1 , 5 As shown in Figure 6, the positioning device 3 includes a first positioning bracket 31, a second positioning bracket 32, and a third positioning bracket 33 arranged in a "T" shape. The T-shaped structure provides stability to the positioning device 3. The first positioning bracket 31 and the second positioning bracket 32 ​​are aligned in a straight line and connected by a connecting plate 34. A connecting block 35 is fixed to the middle of the connecting plate 34, and the connecting block 35 is fixedly connected (e.g., by screws) to one end (e.g., the front end) of the lower mold 2. The third positioning bracket 33 is fixedly connected (e.g., by screws) to the other end (e.g., the rear end) of the lower mold 2. It should be understood that in some embodiments, the connecting block 35 may be omitted. The first positioning bracket 31, the second positioning bracket 32, and the third positioning bracket 33 are all L-shaped and equipped with height-adjustable support members 311, 321, and 331. The support members 311, 321, and 331 are used to support the blank clamping device 4. In the illustrated embodiment, the support members 311 and 321 of the first positioning bracket 31 and the second positioning bracket 32 ​​are L-shaped, and the support member 331 of the third positioning bracket 33 is square. When the support height needs to be adjusted, the screws are loosened, and the support members 311, 321, and 331 are moved to the desired height and then tightened. Preferably, the first positioning bracket 31, the second positioning bracket 32, and the third positioning bracket 33 are provided with scales to improve the adjustment accuracy and efficiency of the support members 311, 321, and 331. In this embodiment, the horizontal length of the first positioning bracket 31, the second positioning bracket 32, and the third positioning bracket 33 can be adjusted to accommodate blank clamping devices 4 of different sizes.

[0045] like Figure 7 As shown, a method for manufacturing a float for an amphibious aircraft according to the present invention includes the following steps:

[0046] S1: Provide a stamping die as described above, wherein the upper die and the lower die are fixed on a hot press.

[0047] S2: Preparation of the blank: The thermoplastic composite material is processed (e.g., cut) to a certain size to obtain the blank to be stamped. The thermoplastic composite material includes thermoplastic resin and reinforcing fibers. The reinforcing fibers can be unidirectional or woven glass fibers, carbon fibers, or polyimide fibers, etc.; the thermoplastic resin can be polypropylene (PP), polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), or polyphenylene sulfone (PPSU), etc. The blank can be cut using methods such as water jet cutting, laser cutting, mechanical cutting, or grinding.

[0048] S3: Heating of the billet: The billet is fixed using the billet clamping device and then placed into the heating equipment for heating. During the heating process, the billet temperature should be 50-100°C higher than the resin melting temperature, preferably 100°C, and the heating time should be 3-10 minutes, preferably 5 minutes.

[0049] S4: Hot stamping. The blank taken from the heating equipment is quickly transferred to a preheated stamping die for stamping. After stamping, it is held at temperature and pressure for a period of time before being removed to obtain the float blank. During the stamping process, the stamping speed is 50-100 mm / min, the stamping pressure is 1-5 MPa, the die temperature should be at least 10°C lower than the glass transition temperature of the resin matrix, and the holding time should be no less than 1 minute, preferably 3 minutes.

[0050] S5: Edge trimming. The float material is trimmed according to the designed dimensions to obtain the float.

[0051] Experimental comparison

[0052] Example 1

[0053] The manufacturing process of amphibious aircraft floats using the manufacturing method of this invention is as follows:

[0054] (1) The carbon fiber reinforced PAEK resin matrix composite material (thermoplastic composite material) is processed according to the dimensions to obtain the blank to be stamped.

[0055] (2) The billet is fixed by the designed billet clamping device and placed into the heating equipment for heating. After heating for 3 minutes, the billet temperature is about 400℃.

[0056] (3) The blank taken out from the heating equipment is quickly transferred to the 120℃ stamping die for stamping. After completion, the holding pressure is 5MPa and the holding time is 3min. The float blank is then taken out.

[0057] (4) The float material is trimmed according to the designed dimensions to obtain the amphibious aircraft float of the present invention.

[0058] Example 2

[0059] The manufacturing process of amphibious aircraft floats using the manufacturing method of this invention is as follows:

[0060] (1) The T800S carbon fiber reinforced PEEK resin matrix composite material (thermoplastic composite material) is processed according to the dimensions to obtain the blank to be stamped.

[0061] (2) The billet is fixed by the designed billet clamping device and placed into the heating equipment for heating. After heating for 5 minutes, the billet temperature is about 430℃.

[0062] (3) The blank taken out from the heating equipment is quickly transferred to the 120℃ stamping die for stamping. After completion, the holding pressure is 5MPa and the holding time is 5min. The float blank is then taken out.

[0063] (4) The float material is trimmed according to the designed dimensions to obtain the amphibious aircraft float of the present invention.

[0064] The amphibious aircraft floats prepared in Examples 1 and 2 were subjected to impact resistance tests. The impact energy was 6.67 J / mm. The dent depth and damage area in the impact resistance test are shown in Table 1 below.

[0065] Comparative Example 1

[0066] The specific process for manufacturing amphibious aircraft floats using existing molding processes (e.g., prepreg molding) is as follows:

[0067] (1) First, the epoxy resin-based composite material (thermosetting composite material) prepreg is laid in the mold and then the mold is closed.

[0068] (2) Place the mold in the press and heat it at a rate of 2℃ / min. Then, solidify it according to the process of 90℃ / 0.4MPa / 30min + 125℃ / 0.55MPa / 120min and let it cool down naturally.

[0069] (3) After the mold is opened, the raw material of the float structure is trimmed according to the designed dimensions to obtain the amphibious aircraft float.

[0070] The amphibious aircraft float prepared in Comparative Example 1 was subjected to impact performance testing. The impact energy was 6.67 J / mm. The dent depth and damage area in the impact performance test are shown in Table 1 below.

[0071] Table 1 Impact resistance performance test

[0072] type Indentation depth / mm <![CDATA[Injury area / mm 2 > Example 1 0.5 585 Example 2 0.5 468 Comparative Example 1 0.6 1150

[0073] The comparison of the dent depth and damage area after impact in Examples 1 and 2 and Comparative Example 1 shows that the impact resistance of the amphibious aircraft floats made of thermoplastic composite materials and the method of the present invention is significantly better than that of the existing amphibious aircraft floats.

[0074] In addition, the inventors also used ultrasonic A-scanning to conduct internal quality tests on the amphibious aircraft floats manufactured in Example 1, such as... Figure 8 As shown. From Figure 8 As can be seen, the bottom wave is relatively strong, and there is no obvious clutter in front, indicating that the internal quality is relatively good and there are no obvious void defects.

[0075] Compared to thermosetting composite material amphibious aircraft floats, amphibious aircraft floats made of thermoplastic composite materials have the following advantages:

[0076] 1. Thermoplastic composite amphibious aircraft floats have good toughness and superior impact resistance and fatigue resistance.

[0077] 2. Amphibious aircraft floats need to be connected to other components. Drilling holes increases the risk of defects. Components made of thermoplastic composite materials can be welded, reducing assembly steps and not increasing defects.

[0078] 3. Amphibious aircraft floats can be manufactured using a rapid stamping process, which greatly shortens the manufacturing time, improves manufacturing efficiency, and enables rapid mass production.

[0079] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A stamping die for an amphibious aircraft float, characterized by, The amphibious aircraft float is in the shape of a ship body and is hot stamped from thermoplastic composite material, the thermoplastic composite material comprises thermoplastic resin and reinforcing fibers, the stamping die comprises an upper die, a lower die, a positioning device and a blank clamping device, the opposite surfaces of the upper die and the lower die have complementary male and female structures, the positioning device comprises a first positioning bracket, a second positioning bracket and a third positioning bracket in the shape of a "T", wherein the first positioning bracket and the second positioning bracket are connected by a connecting plate, one end of the connecting plate is fixedly connected to the lower die, the third positioning bracket is fixedly connected to the other end of the lower die, the first, second and third positioning brackets are all in the shape of L and are provided with height-adjustable supports; the blank clamping device is installed on the supports and is used for clamping the blank to be stamped, so that the blank is positioned and supported directly above the female structure; the blank clamping device comprises a rectangular frame, four springs and four clamps, wherein one end of the spring is positionally adjustably installed on the rectangular frame and the other end is fixed to the clamp, the spring has a certain rigidity to keep the blank horizontal before stamping, and after stamping is completed, the restoring force of the spring makes the float blank separate from the lower die.

2. The stamping die of claim 1, wherein, The upper die is provided with a positioning protrusion on each side of the male structure, and the lower die is provided with a positioning groove on each side of the female structure, the positioning groove cooperates with the positioning protrusion to limit the stamping stroke of the upper die.

3. The stamping die of claim 1, wherein, The upper die and the lower die are both subjected to polishing treatment, and the surface finish is not less than 10 levels.

4. A method of manufacturing a float for an amphibious aircraft, characterized by, The amphibious aircraft float is in the shape of a ship body and is hot stamped from thermoplastic composite material, the thermoplastic composite material comprises thermoplastic resin and reinforcing fibers, the manufacturing method comprises the following steps: S1: providing the stamping die according to any one of claims 1-3; S2: blank preparation, processing the thermoplastic composite material according to a certain size to obtain a blank to be stamped; S3: blank heating, fixing the blank by using the blank clamping device and then putting it into a heating device for heating as a whole; S4: hot stamping, quickly moving the blank taken out from the heating device into the preheated stamping die for stamping, and then taking it out after a certain period of time of heat preservation and pressure retention, thereby obtaining a float blank; S5: edge cutting treatment, cutting the edges of the float blank according to the designed size, thereby obtaining the float.

5. The manufacturing method according to claim 4, wherein In S3, the temperature of the blank should be higher than the melting temperature of the resin by 50-100℃, and the heating time is 3-10min; in S4, the stamping rate is 50-100mm / min, the stamping pressure is 1-5MPa, the mold temperature is lower than the glass transition temperature of the resin matrix by more than 10℃, and the heat preservation time is not less than 1min.

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