High-temperature polyimide system vacuum bag assembling method

Abstract

The invention discloses a high-temperature polyimide system vacuum bag assembling method which comprises a vacuum bag body and a vacuum nozzle, the vacuum nozzle is used for connecting the vacuum bag body with vacuum equipment, and the high-temperature polyimide system vacuum bag is characterized by further comprising a high-temperature sealing rubber strip, a pressure-sensitive adhesive tape, a high-temperature protective coating and a composite metal gasket; the vacuum bag is of a structure with three sealed sides and one opened side, and the vacuum nozzle is arranged on the surface of the vacuum bag; one end of the vacuum nozzle extends into the vacuum bag, and the end, extending into the vacuum bag, of the vacuum nozzle is provided with an opening shearing area. According to the high-temperature polyimide system vacuum bag assembling method, the curing procedure of a high-temperature product can be met, and the use of the same type of vacuum bag autoclave forming process can be met; the high-temperature curing air tightness problem is effectively improved, the vacuum leakage risk is reduced, the production efficiency and the product percent of pass are improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, in particular to a high-temperature polyimide system vacuum bag assembly method. Background Art

[0002] Advanced composite materials are widely used in the aerospace industry due to their good specific strength and specific stiffness, corrosion resistance, and designability. Among them, polyimide system materials have excellent temperature resistance, with a long-term operating temperature range of -200 to 300°C, and some can even withstand high temperatures of 400-500°C in a short period of time, and have an extremely low thermal expansion coefficient, close to that of metals.

[0003] At present, the traditional vacuum bag plus sealing strip method is used in the vacuum bag autoclave molding process of polyimide system materials. The main material of the sealing strip is synthetic rubber, which has a relatively low tensile strength and is prone to breakage or damage when subjected to large tension or stress. It has poor compatibility with other materials. For example, when used in combination with metal, plastic, or other rubber materials, the synthetic rubber sealing strip will have problems such as poor adhesion and mutual corrosion, affecting the performance and reliability of the entire sealing system. The vacuum bag is made of polyimide material, which is relatively hard and is prone to tearing at the cut. Generally, when used in tooling, a vacuum nozzle and a vacuum bag are required to be used in combination. The vacuum bag is first cut and then the vacuum nozzle is passed through the cut from the inside to the outside. At this time, the vacuum bag is prone to tearing and damage. In addition, since there is no matching high-temperature rubber gasket, the vacuum bag is in direct contact with the metal at the vacuum nozzle, and is sealed by the vacuum nozzle metal gasket, resulting in poor sealing.

[0004] Therefore, we propose a high temperature polyimide system vacuum bag assembly method to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a high-temperature polyimide system vacuum bag assembly method to solve the currently commonly used problems raised by the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for assembling a high-temperature polyimide system vacuum bag, wherein the structural features relied upon for assembling the high-temperature polyimide system vacuum bag include the following: comprising a vacuum bag body and a vacuum nozzle body, wherein the vacuum nozzle body is used to connect the vacuum bag body to a vacuum device, and further comprises a high-temperature sealing adhesive strip, a pressure-sensitive adhesive tape, a high-temperature protective coating and a composite metal gasket; the vacuum bag body is a structure with three sides sealed and one side open, and the vacuum nozzle body is arranged on its surface; one end of the vacuum nozzle body extends into the vacuum bag body, and the end of the vacuum nozzle body extending into the vacuum bag body is provided with a cut region, and the cut region is staggeredly covered with two layers of high-temperature pressure-sensitive adhesive tape for enhancing the tear resistance of the cut; the protruding end of the vacuum nozzle body is connected to a vacuum tube body, and a composite metal gasket and a fastening nut are sequentially sleeved on the outside of the vacuum tube body;

[0007] The assembly method of high temperature polyimide system vacuum bag is as follows:

[0008] Step 1: Clean the tooling packaging area, paste two circles of high-temperature sealing strips in sequence, and paste a circle of medium-temperature sealing strips on the outer circle of the high-temperature sealing strips. The high-temperature sealing strips and the medium-temperature sealing strips are laid side by side without overlapping;

[0009] Step 2: In the vacuum bag body selected vacuum nozzle body placement area, make the high temperature pressure sensitive tape cover two layers at 90 degrees and cut out the vacuum nozzle body cutout;

[0010] Step 3: Paste a circle of high-temperature sealing tape on the base of the vacuum nozzle body, and make sure to cover the base and compact it;

[0011] Step 4: Bond and compact the high-temperature sealing strips of the vacuum bag body and the vacuum nozzle body base, and make sure the cutout of the vacuum bag body is consistent with the thread diameter of the vacuum nozzle body;

[0012] Step 5: Place two layers of high-temperature vacuum bag bodies on the upper and lower sides of the metal gasket of the vacuum nozzle body, and tighten the vacuum nozzle body gasket with bolts.

[0013] Preferably, the high-temperature sealing strip is made of modified polyimide material.

[0014] Preferably, the medium-temperature sealing strip is a gradient degradation type material.

[0015] Preferably, the high-temperature sealing strip is laid in the opening area of ​​the vacuum bag to seal the vacuum bag and form an airtight connection with the vacuum nozzle.

[0016] Preferably, the pressure-sensitive tape is used to wrap the cut area of ​​the vacuum bag.

[0017] Preferably, the high temperature protective coating covers the surface of the vacuum bag body in contact with the vacuum nozzle body.

[0018] Preferably, the vacuum nozzle metal gasket multilayer composite structure comprises a flexible metal layer and a rigid support layer.

[0019] Preferably, the flexible layer is used to enhance the conformability of the vacuum bag, and the rigid layer provides high temperature stable support.

[0020] Compared with the prior art, the invention has the following beneficial effects: the high-temperature polyimide system vacuum bag assembly method can meet the curing procedures of high-temperature products and the use of the same type of vacuum bag autoclave molding process; effectively improve the high-temperature curing airtightness problem, reduce the risk of vacuum leakage, improve production efficiency and product qualification rate, and reduce production costs;

[0021] 1. By setting a high-temperature sealing strip, the viscosity of the high-temperature sealing strip gradually improves as the temperature rises, and the sealing is improved. Two high-temperature sealing strips are laid side by side to increase the contact area with the metal tooling and vacuum bag, thereby increasing the sealing in the high-temperature state.

[0022] 2. Stick a circle of high-temperature sealing strip through the base of the vacuum nozzle, flatten it to completely cover the base. The high-temperature sealing strip is in direct contact with the vacuum bag to ensure airtightness. Before cutting the vacuum bag, use high-temperature pressure-sensitive tape to cover two layers at 90° in an alternating manner in the cut area to effectively prevent the cut edge of the vacuum bag from tearing when it is inserted into the vacuum nozzle.

[0023] 3. Cut the high-temperature vacuum bag to a size no smaller than the vacuum base and cut it according to the diameter of the vacuum nozzle thread, and place it in 2 layers above and below the metal gasket of the vacuum nozzle to prevent the vacuum bag from rotating and tearing when the vacuum nozzle is tightened. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the connection structure between the vacuum bag body and the vacuum nozzle body of the present invention;

[0025] Figure 2 It is a schematic diagram of the front cutaway structure of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of the vacuum nozzle body of the present invention;

[0027] Figure 4 It is a schematic diagram of the top view of the cross-section structure of the vacuum bag body and the pressure-sensitive adhesive tape of the present invention;

[0028] Figure 5 It is a schematic diagram of the packaging area structure of the present invention.

[0029] In the figure: 1. vacuum bag body; 2. vacuum nozzle body; 3. high temperature sealing strip; 4. pressure sensitive tape; 5. vacuum tube body; 6. composite metal gasket; 7. fastening nut. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 The present invention provides a technical solution: a method for assembling a high-temperature polyimide system vacuum bag, wherein the structural features relied on for assembling the high-temperature polyimide system vacuum bag include the following: comprising a vacuum bag body 1 and a vacuum nozzle body 2 body, wherein the vacuum nozzle body 2 body is used to connect the vacuum bag body 1 with a vacuum device, and is characterized in that it also comprises a high-temperature sealing strip 3, a pressure-sensitive tape 4, a high-temperature protective coating and a composite metal gasket 6; the vacuum bag body 1 body is a structure with three sides sealed and one side open, and the vacuum nozzle body 2 is arranged on its surface; one end of the vacuum nozzle body 2 extends into the vacuum bag body 1, and the end of the vacuum nozzle body 2 extending into the vacuum bag body 1 is provided with a cut region, and the cut region is staggeredly covered with two layers of high-temperature pressure-sensitive tape 4 for enhancing the tear resistance of the cut; the protruding end of the vacuum nozzle body 2 is connected with a vacuum tube body 5, and the outside of the vacuum tube body 5 is sequentially sleeved with a composite metal gasket 6 and a fastening nut 6;

[0032] The high temperature vacuum bag assembly method of the present invention is adjusted accordingly according to the material properties without changing the material system. Specific assembly method:

[0033] See also Figure 5 , the packaging area from inside to outside is: high-temperature sealing strip, high-temperature sealing strip and medium-temperature sealing strip; high-temperature sealing strip has poor compatibility with other materials, and poor adhesion with metal tooling and vacuum bag body 1 at room temperature and low temperature; medium-temperature sealing strip has good viscosity at medium and low temperature, which can ensure that the airtightness of vacuum bag body 1 fully meets the curing requirements, and will gradually lose the sealing effect after 200°C, and will produce bubbles from rubber state to solid state and powder state, so medium-temperature sealing strip can only be placed on the outermost layer, and laid side by side with high-temperature sealing strip, without overlap or overlap. The viscosity of high-temperature sealing strip gradually improves and the sealing is improved after the temperature rises. Laying two high-temperature sealing strips side by side increases the contact area with metal tooling and vacuum bag body 1, and increases the sealing at high temperature.

[0034] See also Figure 2 and Figure 3, assembly of the vacuum nozzle body 2 area: stick a circle of high-temperature sealing strip 3 on the base of the vacuum nozzle body 2, flatten it and completely cover the base, the high-temperature sealing strip 3 is in direct contact with the vacuum bag body 1 to ensure air tightness, and use high-temperature pressure-sensitive tape to cover two layers 490° staggered in the cut area before cutting the vacuum bag body 1, which can effectively prevent the cut edge of the vacuum bag body 1 from tearing when it penetrates the vacuum nozzle body 2; cut the high-temperature vacuum bag body 1 to be no smaller than the vacuum base and cut it according to the thread diameter of the vacuum nozzle body 2, and put 2 layers on the upper and lower metal gaskets of the vacuum nozzle body 2 to prevent the vacuum bag body 1 from rotating and tearing the vacuum bag body 1 when the vacuum nozzle body 2 is tightened.

[0035] See also Figure 1 and Figure 4 , packaging area operation method:

[0036] Use a dust-free cloth and appropriate cleaning agent to thoroughly clean the tooling packaging area to ensure that there is no dust, oil or other impurities on the surface to prevent the adhesion of the sealing strip from being affected; check whether the tooling surface is flat to ensure that the sealing material can fit it completely to improve the subsequent sealing effect;

[0037] A circle of high-temperature sealing tape 3 is pasted along the predetermined edge of the packaging area to ensure that the tape is continuous and complete and the edge is flat; the first circle of high-temperature sealing tape 3 directly contacts the tooling, providing a basic sealing function, and at the same time, its high-temperature resistance property meets the airtightness requirement during the high-temperature curing process;

[0038] Next to the first circle of high-temperature sealing rubber strips 3, a second circle of high-temperature sealing rubber strips 3 is pasted on its outer circle, ensuring that there is no gap between the two circles of rubber strips but they do not overlap; the second circle of high-temperature sealing rubber strips 3 further improves air tightness by increasing the contact area, and forms a stable double sealing structure in a high-temperature environment, thereby improving pressure resistance and durability;

[0039] A circle of medium-temperature sealing strip is pasted on the outside of the second circle of high-temperature sealing strip 3, ensuring that it is laid side by side with the high-temperature sealing strip 3 and does not overlap; the medium-temperature sealing strip has good medium-low temperature viscosity, and can effectively compensate for air tightness in the pre-high-temperature curing stage to avoid vacuum leakage, while preventing the high-temperature strip from hardening under low temperature conditions in the early stage of curing, resulting in a weakening of the sealing effect;

[0040] Lay the opening area of ​​the vacuum bag body 1 on the sealing strip in the packaging area to ensure that it fits tightly with the strip; adjust the position of the vacuum bag body 1 to align it with the cut area of ​​the vacuum nozzle body 2 to avoid sealing failure due to misalignment; manually apply pressure or use a clamping device to fix the vacuum bag body 1 to ensure that the sealing strip fits completely with the vacuum bag body 1 to achieve airtight packaging.

[0041] Vacuum nozzle body 2 operation method:

[0042] In the installation area of ​​the vacuum nozzle body 2 selected by the high-temperature vacuum bag body 1, use the high-temperature pressure-sensitive tape 4 to cover two layers at 90 degrees to ensure uniform coverage and firm adhesion; use a special cutting tool to cut a cut consistent with the thread diameter of the vacuum nozzle body 2 in the covered area, and ensure that the cut edge is smooth and burr-free to reduce the tearing effect of stress concentration on the vacuum bag body 1; the double-layer covering design of the pressure-sensitive tape 4 effectively enhances the tear resistance of the cut, which is used for the needs of multiple operations in a high-temperature environment;

[0043] A circle of high-temperature sealing strip 3 is evenly pasted on the surface of the base of the vacuum nozzle body 2, and is flattened with a manual roller to ensure that the sealing strip and the base are seamlessly attached; the high-temperature sealing strip 3 is made of modified polyimide material, which can provide excellent sealing performance in a high-temperature environment and adapt to multiple high and low temperature cycles;

[0044] The vacuum nozzle body 2 is accurately placed in the cut area, so that its base is bonded and compacted with the vacuum bag body 1 through the high-temperature sealing strip 3; the fitting state of the sealing strip is checked to ensure that the airtightness between the base of the vacuum nozzle body 2 and the vacuum bag body 1 is not damaged, and at the same time, the sealing performance is optimized through the bonding pressure distribution device to reduce local pressure concentration;

[0045] When cutting the size of the high-temperature vacuum bag body 1, ensure that its coverage is larger than the size of the base of the vacuum nozzle body 2, and leave an appropriate margin to avoid sealing failure during installation; cut a matching notch at the center of the cut vacuum bag body 1 according to the thread diameter of the vacuum nozzle body 2; place the vacuum bag body 1 on the upper and lower sides of the metal gasket of the vacuum nozzle body 2, 2 layers each, to enhance the sealing performance and prevent the vacuum bag body 1 from being squeezed and damaged when the thread is tightened;

[0046] Align the metal gasket and the vacuum bag body 1 with the installation position of the base of the vacuum nozzle body 2, and install the flexible sealing pad, metal gasket and bolts in sequence; use a torque wrench to tighten the bolts evenly with the set torque value to avoid tearing of the vacuum bag body 1 or a decrease in sealing performance due to over-tightening; the fastening design of the bolts combined with the multi-layer composite structure of the metal gasket provides long-term sealing stability under high temperature conditions, and is easy to disassemble and replace later. This is the entire working process of the high-temperature polyimide system vacuum bag assembly method. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field. The standard parts used in the present invention can all be purchased from the market, and the special-shaped parts can be customized according to the description and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the prior art. Machinery, parts and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be described in detail here.

[0047] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for assembling a high-temperature polyimide system vacuum bag, wherein the structural features of the assembly of the high-temperature polyimide system vacuum bag include the following: comprising a vacuum bag body and a vacuum nozzle body, wherein the vacuum nozzle body is used to connect the vacuum bag body to a vacuum device, and wherein: It also includes a high-temperature sealing strip, a pressure-sensitive tape, a high-temperature protective coating and a composite metal gasket; the vacuum bag body is a structure with three sides sealed and one side open, and the vacuum nozzle body is arranged on its surface; one end of the vacuum nozzle body extends into the vacuum bag body, and the end of the vacuum nozzle body extending into the vacuum bag body is provided with a cut area, and the cut area is staggeredly covered with two layers of high-temperature pressure-sensitive tapes that enhance the tear resistance of the cut; the extended end of the vacuum nozzle body is connected to the vacuum tube body, and the outside of the vacuum tube body is sequentially sleeved with a composite metal gasket and a fastening nut; The assembly method of high temperature polyimide system vacuum bag is as follows: Step 1: Clean the tooling packaging area, paste two circles of high-temperature sealing strips in sequence, and paste a circle of medium-temperature sealing strips on the outer circle of the high-temperature sealing strips. The high-temperature sealing strips and the medium-temperature sealing strips are laid side by side without overlapping; Step 2: In the vacuum bag body selected vacuum nozzle body placement area, make the high temperature pressure sensitive tape cover two layers at 90 degrees and cut out the vacuum nozzle body cut; Step 3: Paste a circle of high-temperature sealing tape on the base of the vacuum nozzle body, and make sure to cover the base and compact it; Step 4: Bond and compact the high-temperature sealing strips of the vacuum bag body and the vacuum nozzle body base, and make sure the cutout of the vacuum bag body is consistent with the thread diameter of the vacuum nozzle body; Step 5: Place two layers of high-temperature vacuum bag bodies on the upper and lower sides of the metal gasket of the vacuum nozzle body, and tighten the vacuum nozzle body gasket with bolts.

2. A high temperature polyimide system vacuum bag assembly method according to claim 1, characterized in that: The high temperature sealing rubber strip is made of modified polyimide material.

3. A high temperature polyimide system vacuum bag assembly method according to claim 1, characterized in that: The medium-temperature sealing strip is a gradient degradation type material.

4. A high temperature polyimide system vacuum bag assembly method according to claim 1, characterized in that: The high temperature sealing strip is laid on the opening area of ​​the vacuum bag to seal the vacuum bag and form an airtight connection with the vacuum nozzle.

5. A high temperature polyimide system vacuum bag assembly method according to claim 1, characterized in that: The pressure-sensitive adhesive tape is used to wrap the cut area of ​​the vacuum bag.

6. A high temperature polyimide system vacuum bag assembly method according to claim 1, characterized in that: The high temperature protective coating covers the surface of the vacuum bag body in contact with the vacuum nozzle body.

7. A high temperature polyimide system vacuum bag assembly method according to claim 1, characterized in that: The vacuum nozzle metal gasket multilayer composite structure comprises a flexible metal layer and a rigid support layer.

8. A high temperature polyimide system vacuum bag assembly method according to claim 7, characterized in that: The flexible layer is used to enhance the conformability of the vacuum bag, and the rigid layer provides high temperature stable support.

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