Integral Molding Die and Method for a Water-Resistant Thermoplastic Composite Rotor

Abstract

The present invention relates to the technical field of composite propeller rotor forming, and specifically relates to an integral forming die and method for a water-resistant thermoplastic composite rotor. The die includes a blade pressing die and an integral die; the integral die includes a female die and a male die. The female die and the male die enclose to form a third cavity for placing a rotor core, a second cavity surrounding the third cavity, and a plurality of first cavities spaced outside the second cavity. The third cavity communicates with the second cavity, and the second cavity communicates with each first cavity; a positioning groove for fixing the rotor core is provided at the center of the bottom surface of the third cavity; a pressing plate is also embedded in the male die, and the plane where the bottom of the pressing plate is located coincides with the top surface of the third cavity. A screw hole penetrates through the upper surface of the pressing plate; wherein, the forming cavity of the blade pressing die includes blade segments having the same shape as each first cavity and a connecting segment provided at one end of the blade segments; a pouring port is further provided on the upper surface of the male die, and the pouring port communicates with the second cavity through a pouring pipeline.

Description

Technical Field

[0001] The invention relates to the technical field of composite propeller rotor molding, and in particular to an integral molding die and method for a water-resistant thermoplastic composite rotor. Background Art

[0002] As an important component of underwater vehicles, propellers can convert the torque output by the power system of the vehicle during navigation into the power required for navigation, so that the vehicle can sail at the required speed. The expanded application of composite materials in propellers will play a huge role in vibration reduction, weight reduction, noise reduction and corrosion resistance of vehicles.

[0003] The existing thermosetting composite propeller rotor hub and rotor blades are mostly prepared by combining "adhesion + local bonding reinforcement", mechanical structure connection, "adhesion + mechanical connection", or by thermosetting prepreg integral layer molding. However, the above molding methods will form a potential stress concentration area at the connection position of the rotor blade and the hub. At the same time, the overall molding process has the concept of layers, and the interlayer strength is low, which will cause the connection position to degrade and fatigue damage to expand under the action of periodic loads and long-term immersion in seawater. In severe cases, it will cause interlayer delamination or matrix cracking at the connection position, resulting in reduced stiffness and strength of the product, seriously affecting its service life. In addition, compared with thermosetting composite rotors, high-performance thermoplastic composite rotors have the characteristics of good toughness, low moisture absorption rate, secondary molding, and intelligent manufacturing. Therefore, the development of high-performance thermoplastic composite materials for large-load, high-rigidity, and marine environment-resistant propeller rotors can provide efficient and reliable propulsion guarantees for a new generation of long-range, high-speed, and highly stealthy heavy-duty aircraft.

[0004] Therefore, in view of the above problems, the present invention urgently needs to provide an integral molding die and method for a water-resistant thermoplastic composite rotor. Summary of the invention

[0005] The technical problem solved by the present invention is to provide an integral molding mold and method for a water-resistant thermoplastic composite rotor. The design of the hub and blades is prepared by an injection molding process to solve the problems of low connection strength between the blades, hub and rotor core in the prior art. The strength of the connection between the blades and the hub of the rotor and the overall stiffness of the rotor can be effectively guaranteed, while the seawater resistance is improved, effectively ensuring the service life of the rotor for underwater vehicles sailing in water for a long time.

[0006] The present invention provides an integral molding die for a water-resistant thermoplastic composite rotor, comprising a blade pressing die and an integral die; the integral die includes a female die and a male die, and the female die and the male die enclose to form a third cavity for placing the rotor core, a second cavity surrounding the third cavity, and a plurality of first cavities spaced outside the second cavity. The third cavity communicates with the second cavity, and the second cavity communicates with each first cavity;

[0007] A positioning groove for fixing the rotor core is provided at the center of the bottom surface of the third cavity;

[0008] A pressing plate is also embedded in the male die, and the plane where the bottom of the pressing plate is located coincides with the top surface of the third cavity. A screw hole for screwing with the rotor core is provided through the upper surface of the pressing plate;

[0009] Wherein, the molding cavity of the blade pressing die includes a blade section having the same shape as each first cavity and a connecting section provided at one end of the blade section, and the cross-sectional area of the connecting section at the end far from the blade section is larger than the cross-sectional area of the other end of the connecting section;

[0010] A pouring port is further provided on the upper surface of the male die, and the pouring port communicates with the second cavity through a pouring pipeline.

[0011] Preferably, the cross-sectional area of the connecting section of the molding cavity of the blade pressing die at the end far from the blade section is 3.5 times the cross-sectional area of the other end of the connecting section, and the length of the connecting section is 15 - 20 mm.

[0012] Preferably, a plurality of ejector holes are also spaced on the bottom of the female die, the model of each ejector hole is φ6, and ejector pins are tightly installed in each ejector hole; during the pouring process, the upper surface of the ejector pin is flush with the bottom of the female die; after the molding is completed, the ejector pin penetrates out of the ejector hole to eject the rotor for demolding.

[0013] The present invention also provides an integral molding method for a water-resistant thermoplastic composite rotor based on the integral molding die for a water-resistant thermoplastic composite rotor, comprising the following steps:

[0014] 1) Lay a certain thickness of thermoplastic resin in the molding cavity of the blade pressing die, pre-press, and after demolding, obtain a blade preform;

[0015] 2) Place the blade preform conformally in the first cavity of the female die, such that one end of the blade preform extends into the second cavity;

[0016] 3) Install the rotor core in the third cavity through the cooperation of the positioning groove and the protrusion below the rotor core, and use fastening screws to connect the pressing plate and the rotor core;

[0017] 4) Place the male die coaxially above the female die and press it tightly, and pour into the second cavity through the pouring port;

[0018] 5) After heating, pressurizing, and heat preservation of the overall mold, demold.

[0019] 6) Machine-process the rotor core to obtain a water-resistant thermoplastic composite rotor.

[0020] Preferably, the blade preform includes a blade segment located in the first cavity and a connecting segment located in the second cavity. The cross-sectional area of one end of the connecting segment away from the blade segment is 3.5 times that of the other end of the connecting segment, and the length of the connecting segment is 15 - 20 mm.

[0021] Preferably, the material of the blade preform is a T700 continuous carbon fiber-reinforced high-performance thermoplastic resin using polyether ether ketone or polyarylether ketone as the matrix, and the material of the resin injected into the second cavity is a T700 short fiber-reinforced thermoplastic resin using polyether ether ketone or polyarylether ketone as the matrix.

[0022] Preferably, multiple groups of continuously arranged staggered grooves are distributed in a diamond shape on the side surface of the rotor core, and the material of the rotor core is TC9 titanium alloy.

[0023] Preferably, multiple ejector holes are also provided at intervals at the bottom of the female mold. The model of each ejector hole is φ6, and a ejector pin is tightly installed in each ejector hole. During the pouring process, the upper surface of the ejector pin is flush with the bottom of the female mold. After heating, pressurizing, and heat preservation, remove the male mold, then remove the fastening screws and the pressing plate, and the ejector pin penetrates through the ejector hole to eject the rotor for demolding.

[0024] Preferably, in step 6), the machining of the rotor core includes coaxial drilling of the rotor core and the formation of splines inside the through hole.

[0025] Preferably, in step 4), the temperature of the injected resin is 400 ± 10 °C; in step 5), the curing process is to heat the mold to 230 - 260 °C and keep it warm for 1 h.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides an integral molding mold and method for a water-resistant thermoplastic composite rotor. After prefabricating the blade preform by a compression molding technique, the blade preform is fixed in the second cavity by spot welding, ensuring the coaxiality between the blade and the hub; and the inner side of the blade preform is designed as an inverted trapezoid, improving the connection strength between the blade root and the hub. Then, through an injection molding process, the integral molding of the blade, hub, and rotor core is achieved. The mold of the present invention is easy to operate and has high manufacturing precision, which can effectively ensure the strength at the connection of the rotor blade and the hub and the overall stiffness of the product. At the same time, it can improve the seawater resistance of the product, effectively guaranteeing the service life of the rotor for underwater vehicles during long voyages in water. Description of the Drawings

[0028] Figure 1 is a schematic diagram (vertical sectional view) of step 4) in the embodiment of the present invention;

[0029] Figure 2 is a schematic diagram (vertical sectional view) of the structure of the overall mold in the embodiment of the present invention;

[0030] Figure 3 is a schematic diagram (three-dimensional view) of the structure of the female mold in the embodiment of the present invention;

[0031] Figure 4 is a schematic diagram (three-dimensional view) of the structure of the water-resistant thermoplastic composite rotor in the embodiment of the present invention;

[0032] Figure 5 is an operation flowchart of the integral molding method of the water-resistant thermoplastic composite rotor in the embodiment of the present invention.

[0033] Wherein: 1. Blade preform; 2. Hub; 3. Rotor core; 4. Male mold; 401. Pouring port; 5. Female mold; 7. Positioning groove; 8. Pressing plate; 801. Screw hole; 9. Fastening screw; 10. Ejection hole; 11. First cavity; 14. Protrusion; 15. Blade. Detailed implementation manners

[0034] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 shown, this embodiment provides an integral molding mold for a water-resistant thermoplastic composite rotor, including a blade pressing mold and an overall mold; the overall mold includes a female mold 5 and a male mold 4. The female mold 5 and the male mold 4 enclose a third cavity for placing the rotor core 3, a second cavity surrounding the third cavity, and a plurality of first cavities 11 spaced outside the second cavity. The third cavity communicates with the second cavity, and the second cavity communicates with each first cavity 11;

[0036] A positioning groove 7 for positioning the rotor core 3 is provided at the center of the bottom of the female mold 5;

[0037] A pressing plate 8 is further provided inside the male mold 4, and the plane where the bottom of the pressing plate 8 is located coincides with the top surface of the third cavity;

[0038] Among them, the forming cavity of the blade pressing die includes a blade segment having the same shape as each first cavity 11 and a connecting segment with an inverted trapezoidal cross-section.

[0039] The present invention provides an integral forming die and method for a water-resistant thermoplastic composite rotor. After prefabricating a blade preform through a pressing forming technique, the blade preform is fixed in the second cavity by spot welding, ensuring the coaxiality between the blade and the hub; and the inner side of the blade preform is designed as an inverted trapezoid, improving the connection strength between the blade root and the hub; then, through an injection molding process, the integral forming of the blade, hub, and rotor core is achieved. The die of the present invention is easy to operate and has high manufacturing precision, which can effectively ensure the strength at the connection between the rotor blade and the hub and the overall stiffness of the product. At the same time, it can improve the seawater resistance of the product, effectively guaranteeing the service life of the rotor for underwater vehicles during long-term underwater navigation.

[0040] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 shown, the included angle between the upper surface of the connecting segment of the forming cavity of the blade pressing die and the horizontal plane is 30°, and the length of the connecting segment is 15 - 20 mm.

[0041] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 shown, multiple ejector holes 10 are also provided at intervals at the bottom of the female die 5, and the model of each ejector hole 10 is φ6.

[0042] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 shown, the present invention provides an integral forming method for a water-resistant thermoplastic composite rotor based on an integral forming die for a water-resistant thermoplastic composite rotor, including the following steps:

[0043] 1) Lay a certain thickness of thermoplastic resin in the forming cavity of the blade pressing die, pre-press, and after demolding, obtain a blade preform 1;

[0044] 2) Fix the blade preform 1 in the first cavity 11 of the female die 5, so that the inner side of the blade preform 1 extends into the second cavity;

[0045] 3) Install the rotor core 3 in the third cavity through the cooperation of the positioning groove 7 and the protrusion 14 below the rotor core 3, and connect the pressure plate 8 and the rotor core 3 through the fastening screw 9;

[0046] 4) Place the male die 4 coaxially above the female die 5 and press it tightly, and inject resin into the second cavity;

[0047] 5) After heating, pressurizing and heat preservation of the overall mold, demold it.

[0048] 6) Machine process the rotor core 3 to obtain a water-resistant thermoplastic composite rotor.

[0049] Among them, in step 3), before installing the rotor core 3, a fiberglass epoxy prepreg fabric protective layer with a thickness of 0.3 mm is randomly formed on its surface.

[0050] The present invention provides an integral molding mold and method for a water-resistant thermoplastic composite rotor. After prefabricating a blade preform through a compression molding technique, the blade preform is fixed in the second cavity by spot welding, ensuring the coaxiality between the blade and the hub; and the inner side of the blade preform is designed as an inverted trapezoid, improving the connection strength between the blade root and the hub; then, through an injection molding process, the integral molding of the blade, hub and rotor core is realized. The mold of the present invention is easy to operate and has high manufacturing precision, which can effectively ensure the strength at the connection of the rotor blade and the hub and the overall stiffness of the product. At the same time, it can improve the seawater resistance of the product, effectively guaranteeing the service life of the rotor for underwater vehicles during long voyages in water.

[0051] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 shown, the cross-section of the part where the blade preform 1 extends into the second cavity is an inverted trapezoid, the angle between its upper surface and the horizontal plane is 30°, and the length of this part is 15 - 20 mm.

[0052] In this embodiment, the blade preform 1 can be fixed in the first cavity 11 of the female mold 5 by spot welding, and the two welding parties are one end of the blade preform 1 close to the rotor core 3 and the epoxy fiberglass composite layer coated on the outer surface of the rotor core 3.

[0053] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 shown, the material of the blade preform 1 is a T700 continuous carbon fiber-reinforced high-performance thermoplastic resin using polyether ether ketone or polyarylether ketone as the matrix, and the material of the resin injected into the second cavity is a T700 short fiber-reinforced thermoplastic resin using polyether ether ketone or polyarylether ketone as the matrix; multiple groups of continuously arranged staggered grooves with a depth of 1 - 2 mm are distributed in a diamond shape on the side surface of the rotor core 3, and the material of the rotor core 3 is TC9 titanium alloy.

[0054] As Figure 1 , Figure 2 ,Figure 3 , Figure 4 , Figure 5 As shown, a plurality of ejection holes 10 are also provided at intervals at the bottom of the female mold 5; during the demolding process, the male mold 4 is removed, then the fastening screws 9 and the pressing plate 8 are removed, and then the female mold 5 is removed through the respective ejection holes 10.

[0055] As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the machining of the rotor core 3 includes coaxial hole opening of the rotor core 3 and the formation of splines inside the through hole.

[0056] In this embodiment, in step 4), the temperature of the injected resin is 400 ± 10 °C; in step 5), the curing process is to heat the mold to 230 - 260 °C and keep it warm for 1 h.

[0057] The present invention also provides an embodiment:

[0058] Among them, the outer diameter of the hub 2 is 90 ± 0.5 mm, the maximum length of a single blade 15 is 88 - 90 mm, the circumference of the outer end face of the blade 15 is 200 mm, and the maximum width of the blade 15 is 4 mm; the outer diameter of the composite rotor is 267 - 269 mm, and the height is 68 - 70 mm; the diameter of the rotor core 3 is 60 mm, and a glass fiber fabric reinforced epoxy prepreg with a thickness of 0.3 mm is provided between the rotor core 3 and the hub 2 to isolate the galvanic corrosion effect generated by the metal (rotor core 3) and the composite material (hub 2) in seawater; the hub 2 part is prepared by injection molding using a T700 chopped fiber reinforced thermoplastic resin with polyether ether ketone or polyarylether ketone as the matrix. When injection molding, the temperature of the chopped material is 400 ± 10 °C, the total injection amount of the chopped material is 400 g, the overall molding die temperature is 230 - 260 °C, and after the injection is completed, the holding time is 1 h;

[0059] The overall molding method of the composite rotor includes the following steps:

[0060] 1) Lay a certain thickness of thermoplastic resin in the forming cavity of the blade pressing mold, pre-press, and after demolding, obtain the blade preform 1;

[0061] 2) Place the blade preform 1 conformally in the first cavity 11 of the female mold 5 so that one end of the blade preform 1 extends into the second cavity;

[0062] 3) Install the rotor core 3 in the third cavity through the cooperation of the positioning groove 7 and the protrusion 14 below the rotor core 3, and use the fastening screw 9 to connect the pressing plate 8 and the rotor core 3;

[0063] 4) Place the male mold 4 coaxially above the female mold 5 and press it tightly, and pour resin into the second cavity through the pouring port 401;

[0064] 5) After heating, pressurizing and heat preservation of the overall mold, demold;

[0065] 6) Machine the rotor core 3 to obtain a water-resistant thermoplastic composite rotor.

[0066] For the composite rotor prepared in this embodiment, after it is installed, it is challenged by soaking in seawater for 180 days. After the test, the prototype is weighed, and the water absorption rate is measured to be 0.4-0.6%. A load of 1000 N is applied to the blade 15 in the direction parallel to the axis of the rotor at the center position 100 mm away from the center of the rotor of the single blade 15. The maximum deformation at the middle of the outer end of the blade 15 is measured to be 0.8 mm.

[0067] Obviously, the above embodiments are only examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for integrally forming a water-resistant thermoplastic composite rotor, characterized in that: The steps include: 1) laying a certain thickness of thermoplastic resin in the molding cavity of a blade pressing mold, pre-pressing, and demolding to obtain a blade preform (1); 2) The integral mold comprises a female mold (5) and a male mold (4), wherein the female mold (5) and the male mold (4) are surrounded by a third cavity for accommodating the rotor core (3), a second cavity arranged outside the third cavity, and a plurality of first cavities (11) arranged at intervals outside the second cavity, wherein the third cavity is connected to the second cavity, and the second cavity is connected to each of the first cavities (11); the blade preform (1) is placed in the first cavity (11) of the female mold (5) in a conforming manner, so that one end of the blade preform (1) extends into the second cavity; 3) installing the rotor core (3) in the third cavity by engaging the positioning groove (7) with the protrusion (14) below the rotor core (3), and connecting the pressure plate (8) and the rotor core (3) using the fastening screws (9); 4) placing the male mold (4) coaxially above the female mold (5) and pressing it tightly, and pouring resin into the second cavity through the pouring port (401); 5) After heating, pressurizing and keeping the whole mold warm, demoulding; 6) Mechanically processing the rotor core (3) to obtain a water-resistant thermoplastic composite rotor; The blade preform (1) comprises a blade segment located in the first cavity (11) and a connecting segment located in the second cavity, the cross-sectional area of ​​one end of the connecting segment away from the blade segment is 3.5 times the cross-sectional area of ​​the other end of the connecting segment, and the length of the connecting segment is 15-20 mm; Before installing the rotor core (3), a glass fiber epoxy prepreg fabric protective layer with a thickness of 0.3 mm is formed on the surface of the rotor core (3), and the blade preform (1) is fixed in the first cavity (11) of the female mold (5) by spot welding, and the welding ends are an end of the blade preform (1) close to the rotor core (3) and the glass fiber epoxy prepreg fabric protective layer covering the outer surface of the rotor core (3).

2. The integral molding method of the water-resistant thermoplastic composite rotor according to claim 1, characterized in that: The material of the blade preform (1) is T700 continuous carbon fiber reinforced high-performance thermoplastic resin using polyetheretherketone or polyaryletherketone as a matrix, and the material of the resin injected into the second cavity is T700 chopped fiber reinforced thermoplastic resin using polyetheretherketone or polyaryletherketone as a matrix.

3. The integral molding method of the water-resistant thermoplastic composite rotor according to claim 2, characterized in that: The side surface of the rotor core (3) is provided with a plurality of groups of continuously arranged staggered grooves distributed in a rhombus shape, and the material of the rotor core (3) is TC9 titanium alloy.

4. The integral molding method of the water-resistant thermoplastic composite rotor according to claim 3, characterized in that: The bottom of the female mold (5) is also provided with a plurality of ejection holes (10) at intervals, each of which has a size of φ6, and an ejector pin is tightly mounted in each of the ejection holes (10); during the pouring process, the upper surface of the ejector pin is flush with the bottom of the female mold (5); after heating, pressurizing and heat preservation, the male mold (4) is removed, and then the fastening screws (9) and the pressure plate (8) are removed, and the ejector pin passes through the ejection hole (10) to eject the rotor out of the mold.

5. The integral molding method of the water-resistant thermoplastic composite rotor according to claim 4, characterized in that: In step 6), the mechanical processing of the rotor core (3) includes coaxially opening a hole in the rotor core (3) and providing a spline inside the through hole.

6. The integral molding method of the water-resistant thermoplastic composite rotor according to claim 5, characterized in that: In step 4), the temperature of the injected resin is 400±10°C; in step 5), the curing process is to heat the mold to 230-260°C and keep it warm for 1 hour.

7. An integral forming die for a water-resistant thermoplastic composite rotor used in the integral forming method for a water-resistant thermoplastic composite rotor as claimed in any one of claims 1 to 6, characterized in that: It includes a blade pressing mold and an overall mold; The integral mold comprises a female mold (5) and a male mold (4), the female mold (5) and the male mold (4) enclosing a third cavity for accommodating the rotor core (3), a second cavity enclosing the third cavity, and a plurality of first cavities (11) arranged at intervals outside the second cavity, the third cavity being in communication with the second cavity, and the second cavity being in communication with each of the first cavities (11); A positioning groove (7) for fixing the rotor core (3) is provided at the center of the bottom surface of the third cavity; A pressing plate (8) is also embedded in the male mold (4), the plane where the bottom of the pressing plate (8) is located coincides with the top surface of the third cavity, and a screw hole (801) for screwing to the rotor core (3) is penetrated through the upper surface of the pressing plate (8); The forming cavity of the blade pressing mold comprises a blade segment having the same shape as each first cavity (11) and a connecting segment arranged at one end of the blade segment, and the cross-sectional area of ​​the connecting segment away from the end of the blade segment is larger than the cross-sectional area of ​​the other end of the connecting segment; The upper surface of the male mold (4) is also provided with a pouring port (401), and the pouring port (401) is connected to the second cavity through a pouring pipe.

8. The integral forming die of the water-resistant thermoplastic composite rotor according to claim 7, characterized in that: The cross-sectional area of ​​the connecting section of the blade pressing mold molding cavity away from the blade segment is 3.5 times the cross-sectional area of ​​the other end of the connecting section, and the length of the connecting section is 15-20 mm.

9. The integral forming die of the water-resistant thermoplastic composite rotor according to claim 8, characterized in that: The bottom of the female mold (5) is also provided with a plurality of ejection holes (10) at intervals, each ejection hole (10) having a size of φ6, and an ejector pin is tightly mounted in each ejection hole (10); during the pouring process, the upper surface of the ejector pin is flush with the bottom of the female mold (5); after molding is completed, the ejector pin passes through the ejection hole (10) to eject the rotor from the mold.

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