A hot adhesive medium diaphragm forming process based on a molten resin matrix

Abstract

The present application relates to a kind of based on the forming process of hot adhesive medium diaphragm of molten resin matrix, belong to the technical field of composite precision forming manufacturing, resin matrix is heated to molten state as hot adhesive medium, especially suitable for the diaphragm forming of thermoplastic composite prepreg or composite laminated board with the hot processing temperature above 300 DEG C, utilize the adhesive force of the tangential adhesion generated to diaphragm by the adhesive of resin matrix under molten state, further promote the forming quality and forming limit of diaphragm, to drive composite material has greater degree and higher quality deformation.

Description

Technical Field

[0001] This invention relates to the field of precision molding and manufacturing technology of composite materials, and specifically to a thermo-viscous medium diaphragm molding process based on a molten resin matrix. Background Technology

[0002] Currently, the main molding technologies for continuous fiber resin-based composite laminate parts are compression molding, automated fiber placement, and thermal insulation molding. Compression molding is prone to problems such as fiber buckling, wrinkling, and even tearing. Automated fiber placement cannot process woven composites. Traditional thermal insulation molding relies on vacuum pump negative pressure to achieve molding, but it cannot apply high pressure, has high requirements for the vacuum sealing environment, and the composite prepreg has severe springback, making shape control difficult.

[0003] Among them, the existing hot-medium fluid-filled diaphragm molding is based on fluid filling and rubber bladder hydraulic molding, which can apply greater pressure. This type of flexible molding process improves the quality and precision of the existing compression molding process, but there is little research on it. Also, because the fluid filling medium is oil or water, it can only mold composite materials within the process temperature window of 300°C. For high-performance thermoplastic composite materials such as CF / PEEK, CF / PEI, and CF / PI prepregs or laminates, the molding is limited by temperature.

[0004] Currently, the Chinese patent application with publication number CN112873909A can realize liquid filling molding of sheet material, but the temperature limit of the liquid filling medium is low (below 300℃), which is not suitable for the diaphragm molding of thermoplastic composite materials CF / PEEK, CF / PEI, and CF / PI. Moreover, it is not conducive to improving the stiffness of the diaphragm and there are problems such as fiber buckling, wrinkling and instability during deformation.

[0005] In addition, the Chinese patent with announcement number CN106142587B reduces the normal pressure outside the prepreg layer to zero by controlling the pressure inside the inner diaphragm bag and the outer diaphragm bag. However, the process is complicated and the materials such as bags and air ducts cannot be used to form thermoplastic composites at high temperatures above 300°C. Summary of the Invention

[0006] In view of the above problems, the present invention provides a thermo-viscous medium diaphragm molding process based on a molten resin matrix. The resin matrix is ​​heated to a molten state as a thermo-viscous medium, which is particularly suitable for diaphragm molding of thermoplastic composite prepregs or composite laminates with a heat treatment temperature of above 300°C. The viscous properties of the resin matrix in the molten state generate a tangential adhesive force on the diaphragm, further improving the molding quality and molding limit of the diaphragm, thereby enabling the composite material to have a greater degree and higher quality deformation.

[0007] One object of the present invention is to provide a process for molding a thermo-viscous dielectric diaphragm based on a molten resin matrix, comprising:

[0008] Materials preparation: Select thermoplastic composite prepreg as the preforming material;

[0009] The thermoplastic composite prepreg processing part includes a thermoplastic composite prepreg laminate 3 or a laminate made by thermoplastic composite lamination process; resin material 15 is selected as the pre-melting medium;

[0010] It is understood that the thermoplastic composite prepreg laminate 3 is obtained by a certain number of thermoplastic composite prepreg layups;

[0011] Commissioning of the thermoviscous diaphragm forming equipment: Select a heating source and a press to connect to the equipment;

[0012] The device includes a concave mold 1, a diaphragm component, a graphite gasket 4, a venting gasket 5, a medium chamber 8, and a temperature monitoring component 9; the concave mold 1 is located above the medium chamber 8; the diaphragm component includes a first diaphragm 2 and a second diaphragm 6; the concave mold 1 and the medium chamber respectively include an upper end, a lower end, and an end face;

[0013] The medium chamber 8 includes a medium groove 7, a vacuum channel 13, and an overflow groove 14; the die includes a die cavity 10.

[0014] Material placement: Fill the medium tank 7 with the resin material until the resin material 15 is horizontal with the upper surface of the medium tank, thus obtaining the filled medium tank;

[0015] A ventilated pad 5 is laid on the outer periphery of the preformed material. A first diaphragm 2 and a second diaphragm 6 are respectively covered on the upper and lower surfaces of the laid ventilated pad and the preformed material to obtain the assembly to be formed after the diaphragms are added. It can be understood that a first diaphragm 2 and a second diaphragm 6 with the same shape and size as the ventilated pad 5 are selected. The second diaphragm 6 is placed on the upper surface of the medium tank after the resin material is filled. A ventilated pad and the preformed material are laid on the upper surface of the second diaphragm 6. The ventilated pad is placed on the outer periphery of the preformed material. The preformed material may or may not contact the ventilated pad. The first diaphragm 2 is covered on the upper surface of the second diaphragm 6 after the ventilated pad and the preformed material are laid. The vent holes of the ventilated pad 5 are connected to the vacuum channel 13 through the overflow groove 14. When the vacuum pump is working, the ventilated pad 5, the first diaphragm 2, and the second diaphragm 6 form a vacuum negative pressure space for the prepreg stack 3.

[0016] The dimensions of the first diaphragm 2 and the second diaphragm 6 are matched with the dimensions of the venting pad 5;

[0017] Specifically, the venting pad includes an outer contour and an inner contour; the shape and size of the outer contour of the venting pad are consistent with the shape and size of the contours of the first diaphragm 2 and the second diaphragm 6; the shape and size of the inner contour of the venting pad are the same as or similar to the shape and size of the contour of the preformed material.

[0018] Place the assembly to be formed on the upper surface of the filled medium tank;

[0019] A graphite pad is placed on the upper surface of the media chamber, and the media chamber is closed using the concave mold 1. The graphite pad is connected to the lower surface of the concave mold 1.

[0020] Start the equipment: After the mold is closed, the graphite gaskets are connected to the cavity mold and the medium chamber respectively, and a certain pressing force is applied to the cavity mold, forming a space to be deformed in the forming cavity;

[0021] Connect one end of the vacuum channel 13 to an external vacuum device to vacuum the assembly to be formed after the diaphragm is applied; it can be understood that vacuuming the assembly to be formed after the diaphragm is applied specifically means vacuuming the space between the first diaphragm and the second diaphragm, so that the prepreg stack under the diaphragm is in a negative pressure state.

[0022] The resin matrix is ​​heated by the aforementioned heating source, and the internal temperature is monitored by a temperature monitor to obtain a molten resin matrix.

[0023] Pressure molding: A first pressure is applied to the molten resin matrix to obtain a preliminary molded part, and then a second pressure is applied, the pressure is held and cooled to obtain a cured molded part.

[0024] It is understood that the first pressure is the upward molding pressure, and the second pressure is the pressure held during the upward curing stage; the upward molding pressure and the upward curing stage pressure can be constant pressure or a dynamically changing pressure loading curve.

[0025] Preferably, the first pressure is less than or equal to the second pressure, that is, the molding pressure is less than the holding pressure to suppress curing rebound;

[0026] In the technical solution of this invention, a certain pressing force is applied to the die, and the graphite gasket between the die and the medium chamber is pressed so that the entire circumferential periphery is sealed, thereby forming a space to be deformed in the cavity; the pressing force also presses the periphery of the diaphragm and the venting gasket at the same time, and then the vacuum channel is connected to an external vacuum device to evacuate the space inside the diaphragm through the venting gasket, forming a vacuum negative pressure, so that the prepreg stack under the diaphragm is in a negative pressure state.

[0027] Preferably, the thermoplastic composite prepreg is a carbon fiber composite or a glass fiber composite;

[0028] Furthermore, the carbon fiber composite material includes CF / PEI, CF / PEKK, CF / LCP, or CF / PI;

[0029] The glass fiber composite material includes GF / PEI, GF / PEKK, GF / LCP or GF / PI;

[0030] Preferably, the resin material is a solid resin matrix block or granules;

[0031] The resin material includes PEI matrix, PEKK, LCP, PI, PPS, PP or PA matrix;

[0032] Preferably, the target temperature is 150-425℃;

[0033] Furthermore, the target temperature is 300-425℃;

[0034] Preferably, the shape of the concave cavity 10 corresponds to the shape of the part to be formed;

[0035] Preferably, the cavity mold 1 is located above the medium chamber, and during use, the preformed material is subjected to a blank holder force and passively squeezed into the cavity mold cavity;

[0036] Furthermore, the die also includes a gasket groove 11;

[0037] The lower end of the concave mold cavity penetrates the lower end surface of the concave mold, and the upper end extends into the interior of the concave mold; the gasket groove is disposed on the lower end surface of the concave mold.

[0038] Furthermore, the medium chamber also includes a gasket groove 12;

[0039] The first gasket groove and the second gasket groove have the same shape and size and are used to place graphite gaskets;

[0040] The overflow groove 14 and the gasket groove 2 are both circumferentially arranged on the upper surface of the medium chamber;

[0041] The upper and lower ends of the vacuum passage penetrate the upper and lower surfaces of the medium chamber, respectively; the upper end of the vacuum passage penetrates one end of the overflow groove.

[0042] The medium tank is located in the middle of the medium chamber; one end of the medium tank penetrates the upper surface of the medium chamber, and the other end extends into the interior of the medium chamber;

[0043] Furthermore, the overflow groove 14 is disposed on the outer ring of the medium groove;

[0044] In one embodiment of the present invention, the venting pad is annular in shape, comprising an inner ring and an outer ring; as shown... Figure 1 ;

[0045] The preformed material is circular in shape;

[0046] Furthermore, the inner ring diameter of the venting pad is greater than or equal to the diameter of the preformed material;

[0047] The thickness of the venting pad is equal to the thickness of the preformed material; furthermore, the graphite pad is annular in shape, including an inner ring and an outer ring; the diameter of the inner ring of the graphite pad is larger than the diameter of the outer ring of the venting pad.

[0048] The overflow channel is annular in shape, comprising an inner ring and an outer ring.

[0049] The inner ring diameter of the overflow groove is greater than or equal to the outer ring diameter of the venting gasket; the thickness of the graphite gasket is equal to the sum of the upper diaphragm thickness, the preformed material thickness, the lower diaphragm thickness, the depth of gasket groove 11, and the depth of gasket groove 2; furthermore, the heating source is located inside the equipment or connected to the outside of the equipment.

[0050] Specifically, the heating source includes a heating furnace connected to the outside of the mold, a heating coil, an electromagnetic induction heating coil, or a heating rod embedded in the mold;

[0051] Furthermore, the pressurization source includes using a hydraulic cylinder connected to a plunger to propel the molten medium upward or using injection molding to apply pressure.

[0052] This invention applies a downward pre-tightening force (edge-pressing force) to the elastic diaphragm and the venting gasket, followed by vacuuming, ensuring that the space formed by the diaphragm and prepreg remains under negative pressure. The prepreg is consistently pressed tightly against the upper and lower diaphragms by equal but opposite pressures. Figure 3 As shown, this effectively alleviates the problem of prepreg fiber buckling during the deformation process. Then, pressure molding is performed using a molten medium, followed by high pressure holding and cooling after molding to suppress springback after curing. Figure 4 As shown.

[0053] The thermoplastic composite thermo-viscous medium diaphragm molding in this invention only requires one step, combining thermo-viscous medium filling diaphragm molding with viscous medium pressure forming in the sheet metal industry, enabling low-cost and high-efficiency molding and curing of high-performance thermoplastic composite prepregs.

[0054] This invention uses a resin matrix as the melting medium, which solves the problem of high-temperature molding of prepregs on the one hand, and utilizes the viscosity of the resin matrix itself to form a viscous tangential force, further improving the molding limit of the diaphragm and driving the deformation of the prepreg during high-temperature processing. It has a greater deformation space and has great practical value for single-step molding of thermoplastic composite materials such as CF / PEEK, CF / PEI, and CF / PI carbon fiber / glass fiber reinforced materials with large curvature and complex surface.

[0055] Compared with the prior art, the present invention has at least the following beneficial effects:

[0056] (1) The molding process of the present invention enables high-quality molding of thermoplastic composite prepregs or laminates with a process window of 300°C or above;

[0057] (2) In this invention, the thermoplastic composite thermo-adhesive medium diaphragm molding only requires one step, and the high-performance thermoplastic composite prepreg molding and curing can be carried out at low cost and high efficiency.

[0058] (3) The present invention utilizes the viscosity of the molten resin matrix to achieve tangential adhesion at the interface between the diaphragm and the resin, thereby further improving the molding limit of the diaphragm and driving a greater degree of deformation of the composite prepreg. Attached Figure Description

[0059] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0060] Figure 1 This is a schematic diagram of the thermo-viscous dielectric diaphragm forming equipment of the present invention;

[0061] Figure 2 This is a flowchart of the resin-based thermo-viscous dielectric diaphragm molding process of the present invention;

[0062] Figure 3 This is a schematic diagram of the vacuum channel and negative pressure application in one embodiment of the present invention;

[0063] Figure 4 This is a schematic diagram illustrating the application of multiple forces in the thermoviscous medium diaphragm forming process in one embodiment of the present invention.

[0064] Figure label:

[0065] 1-Die, 2-Upper diaphragm, 3-Pre-forming material, 4-Graphite gasket, 5-Ventilation gasket, 6-Lower diaphragm, 7-Media tank, 8-Media chamber, 9-Temperature monitoring component, 10-Molding cavity, 11-Gasket groove one, 12-Gasket groove two, 13-Vacuum passage, 14-Overflow groove, 15-Resin material. Detailed Implementation

[0066] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0067] A specific embodiment of the present invention, such as Figure 1-4 This invention discloses a process for molding a thermo-viscous dielectric diaphragm based on a molten resin matrix. To illustrate the effectiveness of the method proposed in this invention, the following detailed embodiments are provided to illustrate the above-mentioned technical solution of this invention:

[0068] Example 1

[0069] Materials preparation: CF / PEEK thermoplastic composite prepreg laminate is selected as the preforming material; PEKK resin matrix block is selected as the pre-melting medium; the shape of the preforming material is circular;

[0070] Debugging the hot viscous medium diaphragm forming equipment: Connect a heating furnace and a press to the outside of the equipment; the equipment includes a concave mold 1, a diaphragm component, a graphite gasket 4, a venting gasket 5, a medium chamber 8, and a temperature monitoring component 9;

[0071] The concave mold 1 is located above the medium chamber. During use, the preformed material is subjected to a pressing force and passively squeezed into the concave mold cavity. The concave mold includes a concave mold cavity 10 and a gasket groove 11. The concave mold cavity 10 is hemispherical in shape. The lower end of the concave mold cavity penetrates the lower end surface of the concave mold, and the upper end extends into the interior of the concave mold. The gasket groove 1 is disposed on the lower end surface of the concave mold.

[0072] The medium chamber includes a medium tank 7, a vacuum passage 13, an overflow groove 14, and a gasket groove 12; the medium tank is located in the middle of the medium chamber; one end of the medium tank penetrates the upper end surface of the medium chamber, and the other end extends into the interior of the medium chamber; the upper and lower ends of the vacuum passage penetrate the upper and lower end surfaces of the medium chamber, respectively; the upper end of the vacuum passage penetrates one end of the overflow groove; the overflow groove 14 and the gasket groove 12 are both circumferentially arranged on the upper end surface of the medium chamber; the overflow groove 14 is located in the medium tank. The outer ring; the first and second gasket grooves have the same shape and size and are used to place graphite gaskets; the venting gasket is annular in shape, including an inner ring and an outer ring; the inner ring diameter of the venting gasket is 120mm and the outer ring diameter is 160mm; the shape and size of the outer contour of the venting gasket are the same as the shape and size of the contours of the first and second elastic diaphragms; the shape and size of the inner contour of the venting gasket are the same as or similar to the shape and size of the contour of the preformed material; the inner ring diameter of the overflow groove is 160mm;

[0073] The diameter of the inner ring of the venting gasket is greater than or equal to the diameter of the preformed material; the thickness of the venting gasket is equal to the thickness of the preformed material; the graphite gasket is annular in shape, including an inner ring and an outer ring; the inner ring diameter of the graphite gasket is 190mm, and the outer ring diameter is 240mm; the thickness of the graphite gasket is equal to the sum of the upper diaphragm thickness, the preformed material thickness, the lower diaphragm thickness, the depth of the first gasket groove, and the depth of the second gasket groove; the diaphragm component includes a first elastic diaphragm and a second elastic diaphragm.

[0074] Material placement: Fill the medium tank 7 with the PEKK resin matrix block until the PEKK resin matrix block is level with the upper surface of the medium tank to obtain the filled medium tank; the diameter of the medium tank is 120mm;

[0075] A first elastic diaphragm and a second elastic diaphragm with the same shape and size as the venting pad are selected. The second elastic diaphragm is placed on the upper surface of the filled medium tank. The venting pad and preformed material are laid on the upper surface of the second elastic diaphragm. The venting pad is placed on the outer periphery of the preformed material. The preformed material may or may not contact the venting pad. The upper surface of the laid venting pad and preformed material is covered with the first elastic diaphragm to obtain the assembly to be formed. The venting holes of the venting pad are connected to the vacuum channel 13 through the overflow groove 14. When the vacuum pump is working, the venting pad 5, the first diaphragm 2, and the second diaphragm 6 form a vacuum negative pressure space for the prepreg stack 3.

[0076] Place the assembly to be formed on the upper surface of the filled medium tank;

[0077] A graphite gasket is placed in the gasket groove 2, and the media chamber is closed using the concave mold 1. The graphite gasket is connected to the gasket groove 1 of the concave mold 1.

[0078] Start the equipment: After the mold is closed, the graphite gaskets are connected to the cavity mold and the medium chamber respectively, and a 500N pressing force is applied to the cavity mold, forming a space to be deformed in the forming cavity;

[0079] One end of the vacuum channel 13 is connected to an external vacuum device to evacuate the space between the first elastic diaphragm and the second elastic diaphragm, so that the prepreg stack under the diaphragm is in a negative pressure state.

[0080] The resin matrix is ​​heated in the heating furnace, and the internal temperature is monitored by a temperature monitor until the target temperature of 360℃-400℃ is reached, thus obtaining a molten PEEK matrix.

[0081] Pressure molding: Apply an upward molding pressure of 0.01-1MPa to the molten PEEK matrix to obtain a preliminary molded part, then apply a pressure of 1MPa-10MPa, hold the pressure and cool to obtain a solidified molded part.

[0082] Example 2

[0083] In Example 1, the PEEK matrix was replaced with a PEI matrix, and the target temperature was 320℃-400℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0084] Example 3

[0085] In Example 1, the PEEK matrix was replaced with a PEKK matrix, and the target temperature was 340℃-400℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0086] Example 4

[0087] In Example 1, the PEEK matrix was replaced with an LCP matrix, and the target temperature was 300℃-425℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0088] Example 5

[0089] In Example 1, the PEEK matrix was replaced with a PI matrix, and the target temperature was 320℃-400℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0090] Example 6

[0091] The prepreg of thermoplastic composite material CF / PEEK in Example 2 was replaced with prepreg of thermoplastic composite material GF / PEI, with a target temperature of 320℃-400℃. Other implementation methods were the same as in Example 2, and the cured molded part was obtained.

[0092] Example 7

[0093] The prepreg of thermoplastic composite material CF / PEEK in Example 3 was replaced with prepreg of thermoplastic composite material GF / PEKK, with a target temperature of 340℃-400℃. Other implementation methods were the same as in Example 3, and the cured molded part was obtained.

[0094] Example 8

[0095] The prepreg of thermoplastic composite material CF / PEEK in Example 4 was replaced with prepreg of thermoplastic composite material GF / LCP, with a target temperature of 300℃-425℃. Other implementation methods were the same as in Example 4, and the cured molded part was obtained.

[0096] Example 9

[0097] The prepreg of thermoplastic composite material CF / PEEK in Example 5 was replaced with prepreg of thermoplastic composite material GF / PI, with a target temperature of 300℃-400℃. Other implementation methods were the same as in Example 5, and the cured molded part was obtained.

[0098] Example 10

[0099] In Example 1, the PEEK matrix was replaced with a PPS matrix, and the target temperature was 280℃-350℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0100] Example 11

[0101] In Example 1, the PEEK matrix was replaced with a PP matrix, and the target temperature was 150℃-180℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0102] Example 12

[0103] In Example 1, the PEEK matrix was replaced with a PA matrix, and the target temperature was 260℃-290℃. Other implementation methods were the same as in Example 1, and the cured molded part was obtained.

[0104] This invention applies a downward pre-tightening force (edge-pressing force) to the elastic diaphragm and prepreg, followed by vacuuming, ensuring the space between the diaphragm and prepreg remains under negative pressure. The prepreg is consistently pressed tightly against the diaphragm by an equal and opposite pressure. Figure 3As shown, this effectively alleviates the problem of prepreg fiber buckling during the deformation process. Then, pressure molding is performed using a molten medium, followed by high pressure holding and cooling after molding to suppress springback after curing. Figure 4 As shown.

[0105] The thermoplastic composite thermo-viscous medium diaphragm molding in this invention only requires one step, combining thermo-viscous medium filling diaphragm molding with viscous medium pressure forming in the sheet metal industry, enabling low-cost and high-efficiency molding and curing of high-performance thermoplastic composite prepregs.

[0106] This invention uses a resin matrix as the melting medium, which solves the problem of difficult high-temperature molding on the one hand, and utilizes the viscosity of the resin matrix itself to form a viscous tangential force, further improving the molding limit of the diaphragm and driving the deformation of the high-temperature processed prepreg, resulting in a greater deformation space. It has great practical value for single-step molding of thermoplastic composite materials such as CF / PEEK, CF / PEI, and CF / PI carbon fiber / glass fiber reinforced materials with large curvature and complex surface.

[0107] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for molding a thermo-viscous dielectric diaphragm based on a molten resin matrix, characterized in that, include: Material preparation: Select prepreg materials made from thermoplastic composite materials as preforming materials; Resin material (15) was selected as the pre-melting medium; The thermoplastic composite prepreg is a carbon fiber composite or a glass fiber composite; Debugging the thermoplastic diaphragm forming equipment: The equipment includes a concave mold (1), a diaphragm component, a graphite gasket (4), a venting gasket (5), and a medium chamber (8); the concave mold (1) is located above the medium chamber; the concave mold includes a concave mold cavity (10); the medium chamber includes a medium groove (7); Material placement: Based on the diaphragm and the venting pad (5), the pre-formed material is laid to obtain the assembly to be formed after the diaphragm is added; The pre-melted medium is filled into the medium tank (7) to obtain the filled medium tank; the assembly to be formed is placed on the upper surface of the filled medium tank; The graphite pad (4) is laid on the medium chamber, and the concave mold (1) is closed on the medium chamber after the graphite pad is laid. Start the equipment: After the mold is closed, the graphite gasket is also connected to the concave mold (1), and a certain pressing force is applied to the concave mold, forming a space to be deformed in the cavity of the concave mold; the resin matrix is ​​heated and the assembly to be formed after the diaphragm is applied is vacuumed to obtain a molten resin matrix; Pressure molding: A first pressure is applied to the molten resin matrix to obtain a preliminary molded part, then a second pressure is applied, the pressure is held and cooled to obtain a cured molded part; The diaphragm includes a first diaphragm (2) and a second diaphragm (6); The process of obtaining the preformed assembly with the diaphragm coating specifically includes: laying a ventilation pad (5) on the outer periphery of the preformed material, and applying a first diaphragm and a second diaphragm to the upper and lower surfaces of the laid ventilation pad and the preformed material, respectively, to obtain the preformed assembly with the diaphragm coating. The first pressure is an upward molding pressure, and the second pressure is an upward holding pressure during the curing stage; The first pressure is less than or equal to the second pressure.

2. The thermo-viscous dielectric diaphragm forming process according to claim 1, characterized in that, The processed parts of the thermoplastic prepreg include thermoplastic prepreg laminates (3) or laminates made by thermoplastic composite lamination process.

3. The thermo-viscous dielectric diaphragm forming process according to claim 2, characterized in that, The medium tank (7) is located in the middle of the medium chamber (8); the medium chamber includes an upper end, a lower end and an end face; one end of the medium tank penetrates the upper end face of the medium chamber (8) and the other end extends into the interior of the medium chamber (8); the pre-melted medium is filled into the medium tank (7) until the resin material (15) is level with the upper end surface of the medium chamber, thus obtaining the filled medium tank.

4. The thermo-viscous dielectric diaphragm forming process according to claim 3, characterized in that, The medium chamber also includes a vacuum channel (13); the upper and lower ends of the vacuum channel penetrate the upper and lower surfaces of the medium chamber, respectively.

5. The thermo-viscous dielectric diaphragm forming process according to claim 4, characterized in that, The vacuum channel (13) is connected to an external vacuum device, which is used to vacuum the assembly to be formed after the diaphragm is applied.

6. The thermo-viscous dielectric diaphragm forming process according to claim 5, characterized in that, The medium chamber also includes an overflow groove (14); the overflow groove (14) is disposed on the outer ring of the medium chamber; the overflow groove (14) is circumferentially disposed on the upper surface of the medium chamber; the upper end of the vacuum passage passes through one end of the overflow groove.

7. The thermo-viscous dielectric diaphragm forming process according to claim 6, characterized in that, The medium chamber also includes a second gasket groove (12), and the die also includes a first gasket groove (11); the first gasket groove (11) and the second gasket groove (12) are used to place graphite gaskets.

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