Composite material access cover for pressure testing and method of forming

Abstract

The application discloses a composite material cover for air tightness test and a forming method in the field of composite material products, and belongs to the technical field of composite material products.The composite material cover for air tightness test comprises the following steps: 1) preparing a mold, wherein the mold is a flat plate mold; 2) embedding and laying a prepreg and an inner-outer wire conversion joint, placing two inner-outer wire conversion joint embedded parts in the middle position of the prepreg, and cutting the prepreg to wrap the embedded parts; 3) curing, vacuum bagging the product, and transferring the product into a hot press tank, wherein a vacuum bag is used to extract negative pressure, the hot press tank is used to charge positive pressure, and the final curing process is operated according to the curing parameters of the prepreg until the product is taken out of the tank; and 4) demolding, removing the vacuum bag, and removing the mold to obtain an integrally formed composite material cover with two inner-outer wire conversion joints. The application can meet the air tightness requirement and the strength requirement of the composite material cover, and can simply and efficiently complete the air tightness test. In addition, the application can solve the problem of air leakage of the resin-based composite material after being combined with metal, and can meet the air tightness requirement, the strength requirement, improve work efficiency and reduce manufacturing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to a forming method of a composite material cover, in particular to a composite material cover for tightness test and a forming method. BACKGROUND

[0002] The hull tightness test refers to checking whether the liquid cabin and other cabins of the hull meet the requirements of water tightness or weather tightness. Common tightness test methods include water filling method, water flushing method, kerosene coating detection method, compressed air method and vacuum test method. The compressed air method is widely used because of its good labor conditions, clean operation environment, high inspection sensitivity and suitability for detecting closed hull cabins. The compressed air method fills air into the closed space through an air inlet device, closes the valve after reaching the test air pressure, maintains for a certain period of time, checks whether the pressure will decrease, if the air pressure does not decrease significantly, the test is qualified, and the valve is opened to discharge the gas in the space; if the air pressure decreases significantly, it indicates that the closed space leaks, and the test is unqualified.

[0003] The traditional cover for tightness test is mostly made of steel or aluminum, which is easy to twist and cannot meet the self-airtightness requirements. In addition, it will be corroded by the environment during placement, and will produce metal fatigue after multiple uses. Compared with metal materials, composite materials have strong designability, high specific strength and high specific modulus, and can be used repeatedly. In recent years, composite materials have been widely used in the fields of aerospace, automobiles, buildings, electronic products and sports equipment. In addition, after the metal part is combined with the resin-based composite material, there is generally a gas leakage problem. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application provides a composite material cover for tightness test and a forming method, which forms an integrally formed composite material cover with two inner and outer thread conversion joints, and simultaneously meets the self-airtightness and strength requirements, and simply and efficiently completes the tightness test; solves the problem of gas leakage after the resin-based composite material is combined with the metal, so as to meet the air tightness requirement, the strength requirement, improve the work efficiency and reduce the manufacturing cost.

[0005] The purpose of the present application is achieved by a forming method of a composite material cover for tightness test, comprising the following steps:

[0006] 1) blanking: taking carbon fiber prepreg from a freezer, cooling at room temperature and waiting for use;

[0007] 2) preparing a mold: the mold is a flat plate mold, the mold is degreased and coated with a release agent, and an automatic cloth cutting machine is used to cut the prepreg pieces of each angle required for the lay-up and wait for use;

[0008] 3) surface treatment of carbon steel joint: sandblasting the surface of the carbon steel joint, and the joint after sandblasting needs to be pasted with a film within a certain time;

[0009] 4) Joint wrapping film: after sandblasting, the lower end of the joint is wrapped with a film, and after wrapping, the surface is laid with non-porous release film, air-permeable felt, vacuum bag film, and connected to the vacuum nozzle for vacuumizing;

[0010] 5) Prepreg and inner and outer wire conversion joint pre-embedded laying: place two inner and outer wire conversion joint pre-embedded parts in the middle position of the prepreg, and cut the prepreg to wrap the pre-embedded parts;

[0011] 6) Bag making: after the laying is finished, trim off the messy and redundant prepreg above the lower end of the joint, remove the pre-vacuum bag, lay the peelable cloth and the whole laying release film, wrap the upper end of the joint with an appropriate amount of raw silicone, and then lay the air-permeable felt, vacuum bag film and vacuum nozzle in turn, and vacuumize and shape;

[0012] 7) Curing: after the bag making is completed, transfer to the hot press tank, vacuumize the vacuum bag, pressurize the hot press tank, run the final curing process according to the curing parameters of the prepreg, and until the tank is out;

[0013] 8) Demolding: remove the vacuum bag and remove the mold to obtain an integrally formed composite material cover with two inner and outer wire conversion joints.

[0014] As a further limitation of the present application, step 5) specifically comprises:

[0015] 5-1) Lay fifteen layers of cut carbon fiber prepreg on the mold, lay non-porous release film, air-permeable felt, and vacuum bag film on the surface, and connect the vacuum nozzle to vacuumize;

[0016] 5-2) Open the vacuum bag, position two joint placement positions at a distance on the center line of the carbon fiber prepreg in the length direction, place the pre-embedded parts from bottom to top, and then continue to lay fifteen layers of carbon fiber prepreg, cut at the joint and wrap the pre-embedded parts, seal the pre-vacuum bag, and continue to vacuumize.

[0017] As a further limitation of the present application, the sandblasting parameters of the sandblasting treatment in step 3) are 100 mesh quartz sand, air pressure: 0.6~0.8MPa, inclination between sandblasting nozzle and sandblasted surface: 30°~60°, distance between sandblasting nozzle and joint: 150mm~300mm, and translation speed of sandblasting nozzle: 0.5~1m / min; the sandblasted joint needs to be pasted with a film within 6h.

[0018] Another aspect of the object of the present application is achieved by a composite material hatch cover for tightness test, comprising a hatch cover body, a quick connector gas valve and a pressure gauge are arranged on the hatch cover body, two inner and outer thread conversion connectors are arranged on the hatch cover body, the upper ends of the two inner and outer thread conversion connectors are respectively connected with the quick connector gas valve and the pressure gauge, and the lower ends are communicated with the hull tightness space, and the hatch cover body transmits gas to the hull tightness space through the gas inlet and outlet channel in the quick connector gas valve.

[0019] As a further limitation of the present application, the quick connector gas valve is internally provided with a gas inlet and outlet channel for gas transmission, and the quick connector gas valve controls the on-off of the gas inlet and outlet channel.

[0020] As a further limitation of the present application, the quick connector gas valve is arranged separately from the pressure gauge.

[0021] As a further limitation of the present application, the quick connector gas valve is threadedly connected with the hatch cover body, and the pressure gauge is threadedly connected with the hatch cover body.

[0022] As a further limitation of the present application, the upper end of the quick connector gas valve is connected with a gas pipe.

[0023] The above technical scheme is adopted in the present application, compared with the prior art, and has the beneficial effects that: the hatch cover body is prepared from composite material and resin, does not contain any metal, has relatively low density, and meets the requirements of small mass and light weight; the body prepared from carbon fiber prepreg can be repeatedly used. The preform lamination and autoclave molding method is adopted, the raw material used is preform, the quality is controllable and the performance is stable, the porosity of the composite material is reduced, and the air tightness and strength thereof are improved. The hatch cover body is integrally formed, which is simple, fast and ensures the sealing between parts; the hatch cover body is threadedly connected with the quick connector gas valve and the pressure gauge, which ensures the sealing and is simple to operate and use; the quick connector gas valve simultaneously controls the on-off of the gas inlet and outlet, which is convenient to operate; a good tightness test hatch cover can effectively shorten the test period and improve the work efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0025] Figure 1 The process flow of the method of the present application.

[0026] Figure 2 The structure diagram of the hatch cover of the present application.

[0027] Wherein, 1 inlet and outlet air passage, 2 quick connector air valve, 3 pressure gauge, 4 cap body. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] As Figure 1 shown in a composite cap forming method for tightness test, the thread specification of the joint in the embodiment is M14*1.5, the length is 1.5 inches, the material is carbon steel, T700 / E1301 unidirectional prepreg is used, and the method specifically comprises the following steps:

[0030] Step 1) blanking: T700 / E1301 prepreg is taken out from a freezer, cooled for more than 6 hours under room temperature conditions, and used; the cutting and laying of the prepreg are very convenient, different orientations of fibers can be realized, and the uniform distribution of resin content effectively guarantees the performance and quality of the product while improving the process efficiency;

[0031] Step 2) preparing a mold: the mold is a flat plate mold, the mold is degreased and coated with release agent for more than three times, with an interval of more than 15 minutes each time; an automatic cloth cutting machine is used to cut the prepreg pieces of different angles required for the layers, and the pieces are used;

[0032] Step 3) sandblasting treatment of carbon steel joint: the sandblasting parameters are 100 mesh quartz sand, air pressure: 0.6~0.8MPa, the inclination between the sandblasting nozzle and the sandblasted surface is 30°~60°, the distance between the sandblasting nozzle and the joint is 150mm~300mm, and the translation speed of the sandblasting nozzle is (0.5~1) m / min. The joint after sandblasting needs to be pasted with a film within 6 hours;

[0033] Step 4) joint wrapping film: the lower end of the joint after sandblasting is wrapped with a film, after wrapping, the surface is laid with a non-porous release film, a breathable felt, and a vacuum bag film connected to a vacuum nozzle, and vacuum is drawn for more than 15 minutes, so that the joint is tightly bonded with the film;

[0034] Step 5) Prepreg and inner-outer wire conversion joint pre-embedded laying: Place two inner-outer wire conversion joint pre-embedded parts in the middle position of the prepreg, and cut the prepreg to wrap the pre-embedded parts; Lay 15 layers of T700 / E1301 prepreg on the mold, lay the non-porous release film, air-permeable felt, and vacuum bag film connected to the vacuum nozzle on the surface, and vacuum for more than 15 minutes; After the vacuum bag is opened, position the two joints at a distance on the middle line of the length direction of the carbon fiber prepreg, then place the pre-embedded parts from bottom to top, and then continue to lay 15 layers of carbon fiber prepreg, wrap the pre-embedded parts, seal the vacuum bag, and continue to vacuum for more than 15 minutes.

[0035] Step 6) Bag making: After the laying is completed, trim the excess prepreg above the lower end of the joint to prevent demolding difficulty in the later stage, remove the vacuum bag, lay the peelable cloth, the whole laying release film, wrap the upper end of the joint with an appropriate amount of raw silicone to make it round and not easy to burst, then lay the air-permeable felt, the vacuum bag film, and the vacuum nozzle in turn, vacuum and shape, and detect the vacuum bag to ensure no air leakage;

[0036] Step 7) Curing: After the bag making is completed, transfer to the hot press tank, select 0.2 MPa external pressure and 125°C for 3h to ensure the air tightness and appearance quality of the cover according to the T700 / E1301 prepreg resin system;

[0037] Step 8) Demolding: Remove the vacuum bag and the mold to obtain an integrally formed composite material cover with two inner-outer wire conversion joints.

[0038] As shown in Figure 2 A composite material cover for tightness test, comprising a cover body 4, a quick connector gas valve 2 and a pressure gauge 3 are arranged on the cover body 4; two inner-outer wire conversion joints are arranged on the cover body 4, the upper ends of the two inner-outer conversion joints are respectively connected to the quick connector gas valve 2 and the pressure gauge 3, and the lower ends are communicated with the hull tightness space; an inlet and outlet gas passage 1 is arranged in the quick connector gas valve 2, and the inlet and outlet gas passage 1 is used for gas transmission; the cover body 4 transmits gas to the hull closed space through the inlet and outlet gas passage 1 in the quick connector gas valve 2; the quick connector gas valve 2 controls the on-off of the inlet and outlet gas passage 1; a nut is arranged at the lower end of the quick connector gas valve 2, the thread specification is M14*1.5, the quick connector gas valve 2 is threadedly connected with the cover body 4; a nut is arranged at the lower end of the pressure gauge 3, the thread specification is M14*1.5, and the pressure gauge 3 is threadedly connected with the cover body 4; a gas pipe is connected to the upper end of the quick connector gas valve 2; the quick connector gas valve 2 and the pressure gauge 3 are arranged at intervals, so that when the value of the pressure gauge 3 is observed, the quick connector gas valve 2 can be quickly closed, thereby stopping the gas inlet in the first time when the quick connector gas valve 2 is closed.

[0039] In the actual process of use, the ship body hatch is polished rough, the cover plate is placed on the hatch, the periphery is fixed by 10mm thick narrow strip dry material hand paste, the sealing property is ensured, the cover body 4 is transmitted to the ship body closed space through the inlet and outlet gas passage 1 in the quick plug joint air valve 2, when the tightness test is carried out, the quick plug joint air valve 2 is opened, compressed air is transported to the ship body closed space through the inlet and outlet gas passage 1, the pressure gauge 3 monitors the cabin air pressure in real time and displays the pressure value. During the test, the pressure is tested according to 5Kpa, 10kpa, 15kpa, 20kpa, 25kpa, 30kpa respectively, the pressure gauge 3 does not drop for 30min, and is qualified. After the test is completed, the quick plug joint air valve 2 is opened to make the gas in the closed space discharge through the inlet and outlet gas passage 1, then the connection between the cover plate and the ship body hatch is released, and the tightness test is completed.

[0040] In the actual process of use, when the quick plug joint air valve 2 or the pressure gauge 3 is damaged, the damaged quick plug joint air valve 2 or pressure gauge 3 can be screwed off and replaced with a new one in time, thereby prolonging the service life of the cover plate. At the same time, the damage of the quick plug joint air valve 2 or the pressure gauge 3 can be avoided, the device cannot be used, and the ship body tightness test is delayed.

[0041] In the actual process of use, the ship body hatch is polished rough, the cover plate is placed on the hatch, the periphery is fixed by 10mm thick narrow strip dry material hand paste, the sealing property is ensured. The cover is transmitted to the ship body closed space through the inlet and outlet gas passage 1 in the quick plug joint air valve 2 to carry out the tightness test.

[0042] The cover body 4 is an integrally formed composite cover plate with two inner and outer thread conversion joints. The two conversion joints are M14*1.5 in screw specification. The upper end outer thread can be matched with the lower end inner thread of the air valve and the pressure gauge 3, so as to be screw connected, and the lower end communicates with the ship body tightness space, so as to more accurately display the cabin air pressure in real time.

[0043] The above examples are only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled persons in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for molding a composite material cap for a tightness test, characterized in that, The method comprises the following steps: 1) blanking: taking the carbon fiber prepreg from the freezer, cooling at room temperature and waiting for use; 2) preparing the mold: the mold is a flat mold, the mold is degreased and coated with release agent, and the automatic cloth cutting machine is used to cut the prepreg pieces of each angle required for the layer to be used; 3) surface treatment of carbon steel joint: sandblasting the surface of the carbon steel joint, and the joint after sandblasting needs to be pasted with a film within a certain time; 4) joint wrapping film: wrapping the lower end of the sandblasted joint with a film, and after wrapping, laying a non-porous release film, air permeable felt, and vacuum bag film on the surface, and connecting a vacuum nozzle to vacuum; 5) embedding and laying the prepreg and inner-outer wire conversion joint: placing two inner-outer wire conversion joint embedded parts in the middle position of the prepreg, and cutting the prepreg to wrap the embedded parts, which specifically includes: 5-1) laying fifteen layers of carbon fiber prepreg pieces on the mold, laying a non-porous release film, air permeable felt, and vacuum bag film on the surface, and connecting a vacuum nozzle to vacuum; 5-2) removing the vacuum bag, positioning the two joint placement positions at a distance on the middle line of the carbon fiber prepreg in the length direction, placing the embedded parts from bottom to top in cross-shaped cutting, and then continuing to lay fifteen layers of carbon fiber prepreg, cutting at the joint and wrapping the embedded parts, sealing the pre-vacuum bag, and continuing to vacuum; 6) bag making: after the layering is completed, trim the messy and redundant prepreg above the lower end of the joint, remove the pre-vacuum bag, lay the peelable cloth and the whole release film, wrap the upper end of the joint with an appropriate amount of raw silicone, and then lay the air permeable felt, vacuum bag film, and vacuum nozzle in turn, and vacuum to shape; 7) curing: after the bag making is completed, transfer to the hot press tank, vacuum the vacuum bag, pressurize the hot press tank, operate the final curing process according to the curing parameters of the prepreg, and until the tank is removed; 8) demolding: remove the vacuum bag and the mold to obtain an integrally formed composite material cover with two inner-outer wire conversion joints.

2. The method of claim 1, wherein, The sandblasting parameters of the sandblasting treatment in step 3) are 100 mesh quartz sand, air pressure: 0.6~0.8MPa, inclination between sandblasting nozzle and sandblasted surface: 30°~60°, distance between sandblasting nozzle and joint: 150mm~300mm, and translation speed of sandblasting nozzle: 0.5~1m / min; the joint after sandblasting needs to be pasted with a film within 6h.

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