Electromagnetic induction autoclave for composite material molding and use method thereof

Abstract

The invention discloses an electromagnetic induction autoclave for composite material forming and a use method thereof, and relates to the field of composite material autoclaves, and the electromagnetic induction autoclave comprises a tank body, a tank cover, a temperature detection system, a cooling system, a power supply, a mold, a high-frequency electromagnetic induction generator and an electromagnetic induction heating system. The mold is composed of a metal mold and a carbon layer, the electromagnetic induction heating system comprises an electromagnetic induction heating sleeve and a control system, and the electromagnetic induction heating sleeve is composed of a heat preservation cylinder made of a non-metal material which is low in heat conductivity and resistant to high temperature and an electromagnetic induction coil capable of generating high-frequency current, so that heat can be directly acted on the mold; the heating efficiency is improved, and efficient curing forming of thick-wall products is achieved; and the method also has the advantages of uniform heating, reduction of curing deformation of composite material products and the like. According to the method, the preparation efficiency and the quality stability of the product can be improved by optimizing the relevant parameters of the heat preservation cylinder, the electromagnetic induction coil and the carbon layer in the mold.

Description

Technical Field

[0001] This invention belongs to the field of composite material autoclaves, specifically relating to an electromagnetic induction autoclave for composite material molding and its usage method. Background Technology

[0002] Traditional autoclaves, both domestically and internationally, primarily employ heating methods such as electric heating and oil heating. Electric heating, due to its simple structure, ease of control, and rapid heating speed, is widely used in autoclaves worldwide. However, both electric and oil heating methods first heat the compressed air, relying on heat transfer from the air to slowly heat the mold and the carbon fiber components on it. When using large or medium-sized molds, the mold temperature rises very slowly. While the air temperature inside the autoclave appears uniform on the surface, the actual mold temperature is much lower than the air temperature. This severely impacts processing quality and speed. Typically, placing the carbon fiber prepreg on the mold and immersing it in the autoclave for heating takes about 6 hours from start to finish, and sometimes 10 hours or more.

[0003] CN205573051 U discloses an autoclave device with microwave heating. Microwave heating can heat only the mold, and heats simultaneously from the inside to the outside of the mold. Because the temperature of the objects around the mold remains almost constant after the mold is heated, the electricity required for heating is often less than half that of electric heating. In addition, because it acts directly on the mold, the heating speed is very fast, achieving cost reduction, efficiency improvement, and environmental protection and energy saving. However, microwave heating cannot be applied to metals, only to materials, and has high requirements for material type, shape, and size, and temperature uniformity is difficult to guarantee.

[0004] CN 104908338 B discloses an electromagnetic induction heating rapid prototyping device for composite materials, consisting of four parts: a housing, an electromagnetic induction heating module, a temperature measuring module, and an integrated control module. The integrated control module controls pressure and temperature, while the electromagnetic induction heating module adjusts the electromagnetic intensity and the time interval of the induction heating pulses. This achieves rapid heating, low energy consumption, and significantly shortens the curing cycle of composite materials, enabling low-cost rapid prototyping. However, this device relies on several electromagnetic induction coils for heating. The coil structure and layout are set according to the shape of the composite material molding die. It uses medium-frequency heating, and the heating uniformity is closely related to the product shape, the number of coils, and the coil arrangement, requiring repeated experimentation to find the ideal configuration. Furthermore, existing high-frequency electromagnetic induction heating devices can only cure thin-walled products. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an electromagnetic induction autoclave for composite material molding and a method of using the same.

[0006] To address the aforementioned technical problems, the present invention adopts the following technical solution: The mold of the electromagnetic induction autoclave of the present invention is composed of a metal mold and a carbon layer. The electromagnetic induction heating system includes an electromagnetic induction heating jacket and a control system. The electromagnetic induction heating jacket consists of a heat-insulating cylinder made of a non-metallic material with low thermal conductivity and high temperature resistance, and an electromagnetic induction coil capable of generating high-frequency current. Under the synergistic action of the control system, power supply, and high-frequency electromagnetic induction generator, the generated high-frequency current is converted into high-frequency electromagnetic flux, thereby not only directly applying heat to the mold, improving heating efficiency, and achieving efficient curing and molding of thick-walled products, but also having the advantage of uniform heating, reducing curing deformation of composite material products. By utilizing the electromagnetic induction autoclave of the present invention, and by determining the thickness of the heat-insulating cylinder, the specifications and winding spacing of the electromagnetic induction coil, the thickness of the carbon layer in the mold, and the distance between its upper surface and the inner surface of the mold cavity, product preparation efficiency can be improved, and it has advantages such as quality stability, making it particularly suitable for the industrial preparation of composite material products.

[0007] This invention relates to an electromagnetic induction autoclave for composite material molding, comprising a tank body, a tank lid, a temperature detection system, a cooling system, a power supply, a mold, a high-frequency electromagnetic induction generator, and an electromagnetic induction heating system. The mold consists of a metal mold and a carbon layer, with slots inside the metal mold and the carbon layer located within these slots. The electromagnetic induction heating system includes an electromagnetic induction heating jacket and a control system. The electromagnetic induction heating jacket consists of an insulation cylinder and an electromagnetic induction coil, with the electromagnetic induction coil spirally wound around the outside of the insulation cylinder. The insulation cylinder is made of a non-metallic material with a thermal conductivity not exceeding 0.11 W / (m·K) and resistance to temperatures above 400°C. The electromagnetic induction coil generates a high-frequency current. The control system is connected to the electromagnetic induction coil for intelligent identification and determining the frequency of the output current based on its specifications and spacing. The high-frequency electromagnetic induction generator is connected to the control system, the power supply, and the electromagnetic induction coil to convert the received high-frequency current into a high-frequency magnetic field, which then generates the heat required for composite material product molding within the metal mold via the electromagnetic induction coil.

[0008] Preferably, the electromagnetic induction autoclave of the present invention further includes a vacuum control module, a pressure control module, and a temperature detection system; the vacuum control module and the pressure control module are integrated on the autoclave body; the vacuum control module is connected to the control system and is used to evacuate the autoclave; the pressure control module and the temperature detection system are connected to the control system and detect temperature changes in different parts of the mold.

[0009] Preferably, the carbon layer has a thickness of 2-4 mm, is located in the groove inside the metal mold, and the minimum distance between its surface and the surface of the mold cavity is 4-6 mm.

[0010] More preferably, the surface of the carbon layer has the same curvature as the inner cavity surface of the metal mold.

[0011] Preferably, the insulation cylinder has a wall thickness of 1-2 mm; the electromagnetic induction coil has a diameter of 4-8 mm and a spiral winding spacing of 10-40 mm.

[0012] Preferably, the non-metallic material includes ceramic fiber felt tubes, aerogel felt tubes, and glass fiber felt tubes.

[0013] This invention also relates to a method of using an electromagnetic induction autoclave for composite material molding, characterized by the following steps: 1) Determine the molding temperature based on the materials and structure of the composite product; 2) Based on the molding temperature determined in step 1), determine the thickness of the insulation cylinder, the specifications and winding spacing of the electromagnetic induction coil, the thickness of the carbon layer in the mold, and the distance between its upper surface and the inner surface of the mold cavity. 3) Place the composite prepreg into an electromagnetic induction autoclave; 4) Start the power supply and control system to perform autoclave molding of composite material products.

[0014] Preferably, in step 2), the maximum temperature for molding the composite material is 320℃~370℃, the thickness of the insulation cylinder is 1~2mm, the diameter of the electromagnetic induction coil is 4~8mm, the center-to-center distance between adjacent coils is 10~25mm, and the thickness of the carbon layer in the metal mold is 2~4mm.

[0015] The advantages of this invention compared to existing technologies are as follows: (1) The mold of this invention adopts a combination of a metal mold and a carbon layer. The carbon layer is located inside the metal mold, and the thickness and position of the carbon layer are reasonably adjusted according to the molding temperature of the cured composite material. This allows the electromagnetic heating method to not only directly apply heat to the mold, replacing the traditional gas conduction heating method, but also to achieve fast heating speed, simple structure, and precise temperature control. Furthermore, it has the advantage of uniform heating, which greatly reduces the curing deformation of the composite material product. Compared with traditional autoclaves, it can reduce energy consumption by more than 30% and increase preparation efficiency by more than 30%. In particular, the energy consumption reduction is even greater for high-temperature autoclaves above 400℃. Moreover, the temperature is more uniform compared with microwave heating. While achieving cost reduction and efficiency improvement, it greatly improves safety and reliability.

[0016] (2) Compared with medium-frequency induction heating, high-frequency electromagnetic induction heating is not limited by product shape, number of coils, or coil arrangement, which greatly improves the applicability of autoclaves and makes them more suitable for industrial manufacturing. This invention achieves efficient curing of thick-walled products by optimizing the material, thickness, and specifications of the insulation layer and adding a carbon layer to the mold, thus solving the problem that high-frequency electromagnetic induction heating equipment cannot cure products with a thickness of more than 5mm.

[0017] (3) Electromagnetic induction heating is used to heat only the composite material molding mold itself, resulting in high heat conversion efficiency. Compared with traditional autoclaves, the energy consumption for processing the same product is reduced by 30% to 40%, making it more suitable for the preparation of high-temperature molded composite materials such as large-size components and polyimide composite materials, thereby improving product preparation efficiency and quality stability. Attached Figure Description

[0018] Figure 1 A schematic diagram of the electromagnetic induction autoclave involved in this invention.

[0019] Legend: 1—Tank body; 2—Tank cover; 3—Control system; 4—Vacuum control module; 5—High-frequency electromagnetic induction generator; 6—Power supply; 7—Cooling system; 8—Cooling fan; 9—Pressure control module; 10—Electromagnetic induction heating jacket; 11—Temperature detection system. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the technical solution.

[0021] Example 1 See Figure 1 The electromagnetic induction autoclave of this embodiment consists of a tank body 1, a tank lid 2, a vacuum control module 4, a high-frequency electromagnetic induction generator 5, a power supply 6, a cooling system 7, a cooling fan 8, a pressure control module 9, an electromagnetic induction heating system, a temperature detection system 11, and a mold. The composite material product molded using the electromagnetic induction autoclave of this embodiment is a T300 grade carbon fiber / polyimide composite material sample, 4 mm thick, with a maximum molding temperature of 320°C.

[0022] Tank 1 is a cylindrical structure with an outer diameter of 5m and a length of 8m, with tank cover 2 and cooling fan 8 on its two sides.

[0023] Vacuum control module 4 is used to perform vacuuming operation on tank 1.

[0024] The electromagnetic induction heating system includes an electromagnetic induction heating jacket 10 and a control system 3. The electromagnetic induction heating jacket 10 is a cylindrical structure with an outer diameter matching the inner diameter of the tank 1 and a length matching the tank 1. It consists of an insulation cylinder and an electromagnetic induction coil, with the electromagnetic induction coil evenly spirally wound around the outside of the insulation cylinder. The insulation cylinder is made of ceramic fiber felt with a thermal conductivity of 0.11 W / (m·K) and a high temperature resistance of 400℃, and is 1 mm thick. The electromagnetic induction coil is spirally wound on the outer surface of the insulation cylinder, with a coil diameter of 4 mm and a center-to-center distance of 10 mm between adjacent coils. The control system 3 employs fully digital phase-shift frequency modulation technology and is connected to the electromagnetic induction coil for intelligent identification. It determines the current frequency of the output signal based on the coil specifications and spacing; in this embodiment, the output current frequency is 15 kHz.

[0025] Pressure control module 9 is used to control the pressure inside the autoclave by pressurizing, stabilizing or depressurizing.

[0026] The temperature detection system 11 consists of five temperature sensors, with a temperature measurement range of 0 to 500°C.

[0027] The mold consists of a metal mold and a carbon layer. The metal mold is made of 45# steel and has a 2mm high groove inside that matches the curvature of its inner cavity surface. The carbon layer is 2mm thick and its structure matches the groove inside the metal mold. The carbon layer is placed inside the groove of the metal mold, with the minimum distance between the upper surface of the carbon layer and the inner cavity surface of the mold being 5mm.

[0028] In this embodiment, the vacuum control module 4 and pressure control module 9 are integrated on the tank body 1 of the electromagnetic induction autoclave. The electromagnetic induction heating sleeve 10 is fixed inside the tank body 1, and the power supply 6 is located on the outer wall of the tank body 1 near the cooling fan 8. The high-frequency electromagnetic induction generator 5 is fixed on the tank body 1 and is connected to the power supply 6 and the electromagnetic induction heating sleeve 10 wires respectively; the two ends of the electromagnetic induction coil of the electromagnetic induction heating sleeve 10 are respectively connected to the high-frequency electromagnetic induction generator 5. The temperature detection system 11 is arranged at different positions of the mold to detect the temperature changes at various positions inside the autoclave and at different parts of the mold. The control system 3 is integrated into the autoclave user interface. By connecting to the tank cover 2, vacuum control module 4, power supply 6, cooling fan 8, pressure control system 9, and temperature detection system 11, it can control the opening and closing of the tank door, vacuuming operation, high-frequency current signal output control, start and stop of the cooling fan 8, pressure control inside the autoclave, and temperature control, so as to achieve coordinated control with the functions of the autoclave. After receiving the output signal from the control system 3, the power supply 6 outputs the high-frequency current corresponding to the output signal to the high-frequency electromagnetic induction generator 5, which converts the high-frequency current into a high-frequency magnetic field, and generates heat inside the metal mold containing the carbon layer through the electromagnetic induction coil for heating.

[0029] When using the electromagnetic induction autoclave of this embodiment to cure the T300 grade carbon fiber / polyimide composite material sample, the steps are as follows: First, the five independent temperature sensors of the temperature detection system 11 are set at the center and four vertices of the template mold, respectively, and the pressure inside the autoclave is set to 2.5MPa by the pressure control module 9.

[0030] Power supply 6 is turned on. After the electromagnetic induction coil is energized, it generates a high-frequency current of 15kHz. This current is output to the electromagnetic induction generator 5 through control system 3 and power supply 6, and converted into a high-frequency magnetic field of 15kHz. This magnetic field generates heat inside the metal mold through the electromagnetic wire, and the T300 grade carbon fiber / polyimide composite material sample is heated by gradient heating to complete the curing.

[0031] Compared to the traditional electric heating autoclave curing method, the electromagnetic induction autoclave curing method of T300 grade carbon fiber / polyimide composite material samples in this embodiment reduces energy consumption by 30%, increases preparation efficiency by 30%, increases material bending strength (1.02 GPa) by 17%, tensile strength (900 MPa) by 13%, and interlaminar shear strength (65 MPa) by 10%.

[0032] Example 2 The difference from Example 1 is as follows: See Figure 1 The electromagnetic induction autoclave of this embodiment also includes a sealing device. The composite material product formed using the electromagnetic induction autoclave of this embodiment is a T700 grade carbon fiber / polyimide composite material sample, 10 mm thick, with a maximum molding temperature of 320°C.

[0033] Tank 1 is a cylindrical structure with a diameter of 5m and a length of 10m, with tank cover 2 and cooling fan 8 on its two sides.

[0034] The sealing device is used to confirm that the autoclave has good sealing and pressure-holding performance after the lid 2 is closed.

[0035] The insulation cylinder of the electromagnetic induction heating jacket 10 is made of glass fiber felt with a thermal conductivity of 0.10 W / (m·K) and a high temperature resistance of 400℃, and is 1.5 mm thick. The electromagnetic induction coil has a diameter of 6 mm and a center-to-center distance between adjacent coils of 20 mm. The frequency of the output current of the control system 3 is 25 kHz.

[0036] A 4mm high groove is cut inside the metal mold. The carbon layer is 4mm thick, and after being placed in the groove of the metal mold, the distance between its upper surface and the inner surface of the mold cavity is 4mm.

[0037] When using the electromagnetic induction autoclave of this embodiment to cure the T700 grade carbon fiber / polyimide composite material sample, the steps are as follows: First, the five independent temperature sensors of the temperature detection system 11 are set at the center and four vertices of the template mold, respectively, and the pressure inside the autoclave is set to 2.5MPa by the pressure control module 9.

[0038] Power supply 6 is turned on. After the electromagnetic induction coil is energized, a high-frequency current with a frequency of 25kHz is generated. This current is output to the electromagnetic induction generator 5 through control system 3 and power supply 6, and converted into a high-frequency magnetic field of 25kHz. This magnetic field generates heat inside the metal mold through the electromagnetic wire, and the T700 grade carbon fiber cloth / polyimide composite material sample is heated in a gradient manner to complete the curing.

[0039] Compared to the traditional electric heating autoclave curing method, the electromagnetic induction autoclave curing method of T700 grade carbon fiber cloth / polyimide composite material sample in this embodiment reduces energy consumption by 31%, increases preparation efficiency by 32%, increases material flexural strength (1920MPa) by 12%, tensile strength (2200MPa) by 21%, and interlaminar shear strength (113MPa) by 17%.

[0040] Example 3 The difference from Example 1 is as follows: See Figure 1 The composite material product formed using the electromagnetic induction autoclave in this embodiment is a T700 grade carbon fiber / polyimide composite material sample, 5mm thick, with a maximum molding temperature of 370℃. The autoclave body 1 in this embodiment is a cylindrical structure with a diameter of 3m and a length of 10m, with the lid 2 and cooling fan 8 located on either side.

[0041] The insulation cylinder of the electromagnetic induction heating jacket 10 is made of aerogel felt with a thermal conductivity of 0.08 W / (m·K) and a high temperature resistance of 400℃, and is 1 mm thick. The diameter of the electromagnetic induction coil is 8 mm, and the center-to-center distance between adjacent coils is 25 mm. The frequency of the output current of the control system 3 is 15 kHz.

[0042] The metal mold is made of 40Cr steel with a 4mm high groove inside. The carbon layer is 3mm thick, and after being placed in the groove of the metal mold, the distance between its upper surface and the inner surface of the mold cavity is 4mm.

[0043] When using the electromagnetic induction autoclave of this embodiment to cure the T700 grade carbon fiber / polyimide composite material sample, the steps are as follows: First, the five independent temperature sensors of the temperature detection system 11 are set at the center and four vertices of the template mold, respectively, and the pressure inside the autoclave is set to 2.5MPa by the pressure control module 9.

[0044] Power supply 6 is turned on. After the electromagnetic induction coil is energized, a high-frequency current with a frequency of 15kHz is generated. This current is output to the electromagnetic induction generator 5 through the control system 3 and power supply 6, and converted into a high-frequency magnetic field of 15kHz. This magnetic field generates heat inside the metal mold through the electromagnetic wire, and the T700 grade carbon fiber cloth / polyimide material sample is heated in a gradient manner to complete the curing.

[0045] Compared to the traditional electric heating autoclave curing method, the electromagnetic induction autoclave curing method of T700 grade carbon fiber / polyimide composite material samples in this embodiment reduces energy consumption by 32%, increases preparation efficiency by 36%, increases material flexural strength (2000MPa) by 10%, tensile strength (2400MPa) by 15%, and interlaminar shear strength (108MPa) by 12%.

[0046] Example 4 The difference from Example 1 is as follows: See Figure 1 The composite material product formed using the electromagnetic induction autoclave in this embodiment is a T800 grade carbon fiber / polyimide composite material sample, 3mm thick, with a maximum molding temperature of 370℃. The autoclave body 1 in this embodiment is a cylindrical structure with a diameter of 7m and a length of 15m, with the lid 2 and cooling fan 8 located on either side.

[0047] The insulation cylinder of the electromagnetic induction heating jacket 10 is made of glass fiber felt with a thermal conductivity of 0.10 W / (m·K) and a high temperature resistance of 400℃, and is 2 mm thick. The diameter of the center line of the electromagnetic induction coil is 5 mm, and the center-to-center distance between adjacent coils is 15 mm. The frequency of the output current of the control system 3 is 25 kHz.

[0048] The metal mold is made of 40Cr steel with a 2mm high groove inside. The carbon layer is 2mm thick, and after being placed in the groove of the metal mold, the distance between its upper surface and the inner surface of the mold cavity is 6mm.

[0049] When using the electromagnetic induction autoclave of this embodiment to cure the T800 grade carbon fiber / polyimide composite material sample, the steps are as follows: First, the five independent temperature sensors of the temperature detection system 11 are set at the center and four vertices of the template mold, respectively, and the pressure inside the autoclave is set to 2.5MPa by the pressure control module 9.

[0050] Power supply 6 is turned on. After the electromagnetic induction coil is energized, a high-frequency current with a frequency of 25kHz is generated. This current is output to the electromagnetic induction generator 5 through the control system 3 and power supply 6, and converted into a high-frequency magnetic field of 25kHz. This magnetic field generates heat inside the metal mold through the electromagnetic wire, and the T800 grade carbon fiber / polyimide composite material sample is heated by gradient heating to complete the curing.

[0051] Compared to the traditional electric heating autoclave curing method, the electromagnetic induction autoclave curing method of T800 grade carbon fiber / polyimide composite material samples in this embodiment reduces energy consumption by 34%, increases preparation efficiency by 40%, increases material flexural strength (2200MPa) by 15%, tensile strength (2100MPa) by 13%, and interlaminar shear strength (105MPa) by 19%.

Claims

1. An electromagnetic induction autoclave for composite material molding, comprising a tank body, a tank lid, a temperature detection system, a cooling system, a power supply, and a mold, characterized in that: It also includes a high-frequency electromagnetic induction generator (5) and an electromagnetic induction heating system; the mold is composed of a metal mold and a carbon layer, with slots inside the metal mold and the carbon layer located in the internal slots of the metal mold; the electromagnetic induction heating system includes an electromagnetic induction heating jacket (10) and a control system (3); the electromagnetic induction heating jacket (10) is composed of an insulation cylinder and an electromagnetic induction coil, with the electromagnetic induction coil spirally wound around the outside of the insulation cylinder; the insulation cylinder is made of non-metallic material with a thermal conductivity not exceeding 0.11 W / (m·K) and resistance to temperatures above 400℃; the electromagnetic induction coil is used to generate high-frequency current; the control system (3) is connected to the electromagnetic induction coil and is used to intelligently identify it and determine the frequency of the output current according to its specifications and spacing; the high-frequency electromagnetic induction generator (5) is connected to the control system (3), the power supply (6) and the electromagnetic induction coil and is used to convert the received high-frequency current into a high-frequency magnetic field and generate the heat required for the molding of composite material products inside the metal mold through the electromagnetic induction coil.

2. The electromagnetic induction autoclave for composite material molding according to claim 1, characterized in that: It also includes a vacuum control module (4), a pressure control module (9), and a temperature detection system (11); the vacuum control module (4) and the pressure control module (9) are integrated on the tank body (1); the vacuum control module (4) is connected to the control system (3) and is used to evacuate the autoclave; the pressure control module (9) and the temperature detection system (11) are connected to the control system (3) and are used to detect the temperature changes of different parts of the mold.

3. The electromagnetic induction autoclave for composite material molding according to claim 1, characterized in that: The carbon layer is 2-4 mm thick and is located in the groove inside the metal mold. The minimum distance between its surface and the surface of the mold cavity is 4-6 mm.

4. The electromagnetic induction autoclave for composite material molding according to claim 3, characterized in that: The surface of the carbon layer has the same curvature as the inner cavity surface of the metal mold.

5. The electromagnetic induction autoclave for composite material molding according to claim 1, characterized in that: The insulation cylinder has a wall thickness of 1-2 mm; the electromagnetic induction coil has a diameter of 4-8 mm and a spiral winding spacing of 10-40 mm.

6. The electromagnetic induction autoclave for composite material molding according to claim 1, characterized in that: The non-metallic materials include ceramic fiber felt tubes, aerogel felt tubes, and glass fiber felt tubes.

7. A method of using the electromagnetic induction autoclave molding method for composite material molding as described in claim 1, characterized in that, The steps are as follows: 1) Determine the molding temperature based on the materials and structure of the composite product; 2) Based on the molding temperature determined in step 1), determine the thickness of the insulation cylinder, the specifications and winding spacing of the electromagnetic induction coil, the thickness of the carbon layer in the mold, and the distance between its upper surface and the inner surface of the mold cavity. 3) Place the composite prepreg into an electromagnetic induction autoclave; 4) Start the power supply (6) and control system (3) to perform autoclave molding of composite material products.

8. The method for molding composite material products using an electromagnetic induction autoclave according to claim 7, characterized in that: In step 2), the maximum temperature for molding the composite material is 320℃~370℃, the thickness of the insulation cylinder is 1~2mm, the diameter of the electromagnetic induction coil is 4~8mm, the center-to-center distance between adjacent coils is 10~25mm, and the thickness of the carbon layer in the metal mold is 2~4mm.

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