One-time forming method for a multi-layer structure resin matrix composite cover

Abstract

The present invention relates to a one - step forming method for a multi - layer structure resin - based composite cover, belonging to the technical field of resin - based composite materials. The finished product of the composite cover is obtained through steps of structural design, mold design, layup, vacuum bag sealing, resin preparation, vacuum injection molding, and room - temperature curing. Thereby, it ensures that the cover has better strength and stability, and has the characteristic of better integrity in structure compared with two - dimensional fiber cloth. The outer layer of the composite cover uses 1 - mm low - density needled felt, and after compounding, a dense surface effect is achieved by relying on a high - content resin, achieving the purpose of enhancing the watertight performance of the composite cover while having high wave - transmission and high mechanical properties; thus meeting the requirements of high - end naval equipment for multi - functional and low - cost composite materials.

Description

Technical Field

[0001] The present invention relates to a one - step forming method for a multi - layer structure resin - based composite cover body, belonging to the technical field of resin - based composite materials. Background Art

[0002] Composite materials are widely used in naval equipment due to their excellent mechanical properties, corrosion resistance (resistant to acid, alkali, seawater erosion, and difficult for aquatic organisms to attach), and excellent acoustic, magnetic, and electrical properties (wave - transmitting, non - magnetic, and excellent dielectric properties). In recent years, more and more metal parts in naval equipment have been replaced by multifunctional composite materials (such as the manufacturing of parts and shells of underwater weapons such as mines and mine - countermeasure devices).

[0003] For products such as antenna cover bodies with long length and small diameter, the earliest process was the hand - lay - up process, that is, hand - laying fabrics on a metal male mold, then brushing resin, and finally curing by vacuum pumping. This process is difficult to operate, has a large workload, and a poor working environment; the uniformity at each position of the product is poor, the product consistency is poor, and a large amount of solvents in the resin volatilize and pollute the environment; moreover, this process is only suitable for preparing products with a relatively large wall thickness. For products with a small wall thickness, because the hand - lay - up process is an open operating environment, it is difficult to meet the requirements of airtightness and watertightness of the product by this process method.

[0004] Subsequently, it was changed to the vacuum - assisted resin infusion process for preparing products such as antenna cover bodies with long length and small diameter. That is, first prepare a cover body fabric preform (the preform is prepared by stitching after two - dimensional fabric lay - up, or three - dimensional integral weaving molding, or using a woven sleeve and then stitching after lamination), then wrap it with a vacuum bag. Under vacuum assistance, the resin is adsorbed into the vacuum bag to infiltrate the resin, and then cured and formed. The cover body products prepared by this process have good mechanical properties, small workload, good working environment, and good product consistency. However, in the actual operation process, it is found that the cover body products prepared by this process have many surface wrinkle defects, are difficult to meet the requirements of airtightness and watertightness, and have a slow resin injection speed, etc. The reasons are as follows: 1. Under the action of vacuum pressure, the fabric of the cover body preform is extruded towards the middle, resulting in more wrinkles in the cover body preform, and the greater the fabric compression amount, the more and deeper the wrinkles; 2. The airtightness and watertightness are related to the airtightness of the vacuum bag and the porosity of the product during the product preparation process. The worse the airtightness of the vacuum bag and the larger the porosity, the more difficult it is to ensure the airtightness of the product; 3. After vacuum pumping, the fabric is compressed and compacted, resulting in a slow resin injection speed.

[0005] Therefore, it is necessary to design a forming process for cover body products, which has a simple process, few related defects such as wrinkles in the product, can meet the requirements of airtightness and watertightness, has a fast resin injection rate, and a high yield rate. Summary of the Invention

[0006] The object of the present invention is to provide a vacuum resin infusion molding method for radome products with high efficiency, few surface defects and high yield. The preform of the radome is made by laminating quartz woven sleeves and then caulking to form a whole. To improve the airtightness of the product, a layer of 0.2 g / cm 3 quartz needle punched felt is added between each layer of woven sleeves. Due to the low density of the quartz needle punched felt, the resin content in this felt layer is high, and its resin mass fraction can be as high as 80%. After laying each layer of the woven sleeve, use a quartz cloth tape to tightly wrap the inner fabric to prevent wrinkles from occurring during the subsequent vacuuming process. Use two layers of vacuum bags to ensure the airtightness requirements during the resin injection and curing processes of the product. During the resin injection process, use multi-stage continuous resin injection to improve the resin injection rate.

[0007] The technical solution of the present invention is as follows:

[0008] A method for one-step molding of a multi-layer structure resin matrix composite radome, characterized by comprising the following steps:

[0009] 1). Structural design: First, disassemble the structural drawing of the radome and conduct structural design on the composite material.

[0010] 2). Mold design: According to the product structure, design a conformable lay-up mold. Leave a resin inlet and a resin pool at the lower end of the lay-up mold, and leave a resin outlet at the top by adding a metal cap at the upper end head position to achieve the resin impregnation process of injecting resin from the bottom and discharging it from the top.

[0011] 3). Lay-up: Adopt the method of spaced lamination to sequentially sleeve the quartz woven sleeve and the needle punched felt on the mold to achieve lay-up. First lay a layer of quartz woven sleeve, then lay a layer of needle punched felt whose shape corresponds to that of the quartz woven sleeve. Connect the quartz woven sleeve and the needle punched felt by needle punching technology at the interface between them. Then use a quartz cloth tape about 50 mm wide to tightly wrap the inner quartz woven sleeve and the needle punched felt. Lay up 4 - 5 cycles in sequence according to this method and order. After the lay-up is completed, connect the whole lay-up by caulking to enhance the interlayer strength and the overall strength, obtaining a semi-finished composite radome.

[0012] 4), Vacuum bag sealing and shaping: After the layup is completed, at every 1 / 3 distance along the length of the cover body, a resin injection port is prepared using a PTFE tube, a three-way joint, and a diversion tube for segmented resin injection. The vacuum bag is sleeved on the semi-finished composite cover body. Among them, the upper end of the vacuum bag is sealed to the metal cap and the glue outlet is exposed, and the lower end of the vacuum bag is sealed to the flange seat and the glue inlet is exposed. After blocking the glue inlet by installing a ball valve at the port of the glue inlet, the first vacuum pumping starts through the glue outlet by the vacuum pump. After the vacuum pumping reaches -0.098 MPa, it is pressurized and maintained for 10 minutes, and the vacuum degree drops no more than 0.01 MPa; after the first vacuum pumping is completed, then repeat the above operation, sleeve another layer of vacuum bag outside the vacuum bag, and conduct the second vacuum pumping. After the second vacuum pumping reaches -0.098 MPa, it is pressurized and maintained for 10 minutes, and the vacuum degree drops no more than 0.01 MPa, then the vacuum degree is qualified; thus, the compression shaping of the semi-finished composite cover body is completed;

[0013] 5), Resin preparation: After mixing and configuring according to the ratio of vinyl resin:diluent:coupling agent:curing agent:accelerator = 100:3:0.5:2.5:1.2, put it into a vacuum drying oven and evacuate and defoam for 10 minutes; reserve for use,

[0014] 6), Vacuum resin injection: Connect the glue inlet of the layup mold to the container filled with resin through the ball valve and the PTFE tube. Under the condition of a vacuum degree not less than -0.095 MPa, make the resin enter the mold under negative pressure to infiltrate the semi-finished composite cover body; when the resin is injected from the bottom up to the injection port at the first 1 / 3 position, put the injection tube at this position into the resin bucket to continue injecting resin at this position. When the resin is injected from the bottom up to the injection port at the second 1 / 3 position, put the injection tube at this position into the resin bucket to continue injecting resin at this position until the resin injection is finally completed. After the glue outlet discharges glue, close the glue inlet, continue to pump vacuum to discharge the excess resin and air bubbles until there are no air bubbles at the glue outlet end, then close the injection port, the glue outlet, and the vacuum pump;

[0015] 7), Room temperature curing: To avoid damage and air leakage of the vacuum bag caused by the movement of the fabric, cure under the condition of normal temperature in place, and the curing time is 24 hours; after the curing is completed, remove the vacuum bag and the layup mold, use sandpaper to polish the burrs of the composite cover body, and at the same time conduct internal flaw detection of the composite cover body using X-rays to obtain the finished composite cover body.

[0016] The laying die described in step 2 includes a cap, a core mold, a base and a bottom plate. The bottom plate is fixedly installed on the base. A cylindrical core mold is arranged on the bottom plate. Positioning blocks are arranged on the lower surface of the bottom plate corresponding to the core mold. Positioning bolts are arranged on the positioning blocks. One end of the positioning bolt passes through the bottom plate and is threadedly connected to the core mold. A flange is arranged on the circumference at the bottom end of the core mold. A flange seat is arranged on the core mold corresponding to the flange. A stepped hole is arranged on the flange seat. The flange seat is connected to the bottom plate through a fixing bolt. The flange seat is in contact connection with the core mold through the cooperation of the stepped hole and the flange.

[0017] A cap is arranged on the top of the core mold, and a glue outlet is arranged on the cap.

[0018] A glue inlet is radially penetrated on the flange seat.

[0019] In step 3, the thickness requirement of the cover body product is 10 - 13 mm.

[0020] In step 3, the thickness of the quartz woven sleeve is 2 mm, the thickness of the needle punched felt is 0.2 - 1.2 mm, and the fiber density of the needle punched felt is 0.2 g / cm 3 .

[0021] In step 4, the structure of the middle glue injection port is as follows: First, wind the diversion tube around the cover body at about 1 / 3 of the length. The two ends of the diversion tube are connected to the two interfaces of the tee. Connect the other interface of the tee with a teflon tube, and pass the teflon tube through the vacuum bag mold and pull it out. Seal the teflon tube and the vacuum bag film with a sealing strip.

[0022] The diluent described in step 5 is styrene, the coupling agent is silane coupling agent KH-560, the curing agent is methyl ethyl ketone peroxide, and the accelerator is cobalt isooctanoate.

[0023] The beneficial effects of the present invention are as follows:

[0024] The present invention realizes laying by sequentially sleeving the quartz woven sleeve and the needle punched felt on the mold in an interval and laminating manner. Among them, the quartz woven sleeve is a woven three-dimensional fabric, which ensures that the fibers at the head and circumferential direction of the cover body are continuous, thereby avoiding wrinkles and fiber breakage caused by laying. During the laying process of the composite material cover body, the joints are connected by needle punching technology, so as to ensure that the cover body has better strength and stability. Structurally, it has better integrity compared with two-dimensional fiber cloth. The outer layer of the composite material cover body uses 1 mm low-density needle punched felt, and after compounding, it achieves a dense surface by relying on a high content of resin. While having high wave transmission and high mechanical properties, it realizes the purpose of enhancing the water tightness performance of the composite material cover body; thus meeting the requirements of high-end naval equipment for multi-functional and low-cost composite materials.

[0025] In the present invention, the fabric structure adopts a structural form of alternating quartz woven sleeves and needle-punched felt layers. This not only ensures that the product has high mechanical strength but also has a resin-rich layer in the form of a multi-layer needle-punched felt / resin structure. The mass fraction of the resin in this resin-rich layer can reach 80% (obtained through calculation), ensuring the airtight and watertight requirements of the product. The present invention uses a double-layer vacuum bag film to evacuate the air and adopts a multi-stage continuous injection method during the injection process. Through the design of relevant processes, the stability, reliability of the process and the yield rate of the product are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the laying mold of the present invention;

[0027] Figure 2 is a sectional structural diagram of the laying mold of the present invention.

[0028] In the figure: 1, base; 2, bottom plate; 3, glue inlet; 4, flange seat; 5, core mold; 6, cap; 7, glue outlet; 8, positioning block; 9, positioning bolt. DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiment 1

[0029] First, disassemble the structure diagram of the cover body, and design the structure of the composite material according to the disassembly diagram. The inner layer is designed as a porous structure of a corrosion-resistant vinyl resin composite quartz fiber woven sleeve, and the outer layer is designed as a dense structure of a vinyl resin composite low-density quartz needle-punched felt. It is required that the inner layer has excellent radial mechanical properties and high water pressure resistance, and the dense outer layer structure can ensure the watertightness of the product. The overall material has good wave-transmitting properties and can meet the requirements of the product for mechanical properties, wave-transmitting properties and watertight properties at the same time. At the same time, it is designed to be formed by one-time injection molding, and the integrity of the product is better;

[0030] Design the laying mold according to the product structure. The laying mold includes a cap 6, a core mold 7, a base 1 and a bottom plate 2. The bottom plate 2 is fixedly installed on the base 1. A cylindrical core mold 5 is arranged on the bottom plate 2. A cap 6 is arranged on the top of the core mold 5, and a glue outlet 7 is arranged on the cap 6. A positioning block 8 is arranged on the lower surface of the bottom plate 2 corresponding to the core mold 5, and a positioning bolt 9 is arranged on the positioning block 8. One end of the positioning bolt 9 passes through the bottom plate 2 and is threadedly connected to the core mold 5, thereby realizing the fixation of the core mold 5 on the bottom plate 2; a flange is arranged on the circumference at the bottom end of the core mold 5, a flange seat 4 is arranged on the core mold 5 corresponding to the flange, and a glue inlet 3 is arranged on the flange seat 4 in a radially penetrating manner. A stepped hole is arranged on the flange seat 4, and the flange seat 4 is connected to the bottom plate 2 through a fixing bolt. The flange seat 4 is in contact connection with the core mold 5 through the cooperation of the stepped hole and the flange, thereby realizing the seal between the flange seat 4 and the core mold 5. A sealing ring is arranged between the flange seat 4 and the core mold 5 and the bottom plate 2 to realize the seal between the flange seat 4 and the core mold 5 and the bottom plate 2.

[0031] Layering: In an alternating layer-by-layer manner, a quartz woven sleeve and a needled felt are successively sleeved on a mold to achieve layering. First, lay a layer of quartz woven sleeve, then lay a layer of needled felt, whose shape corresponds to that of the quartz woven sleeve. The quartz woven sleeve and the needled felt are connected by needling technology at their interface. Then, use a quartz cloth tape about 50 mm wide to tightly wrap the inner quartz woven sleeve and the needled felt. Layering is carried out in 6 cycles in accordance with this method and sequence. Among them, the thickness of the quartz woven sleeve is 2 mm, the thickness of the needled felt is 0.2 mm, and the overall thickness is 13.2 mm. After layering is completed, the entire layered structure is connected by hook stitching to enhance the interlayer strength and overall strength, obtaining a semi-finished composite material cover body.

[0032] After the semi-finished composite material cover body is prepared, at every 1 / 3 distance along the length direction of the cover body, a resin injection port is prepared using a PTFE tube, a three-way joint, and a diversion tube for segmented injection. The vacuum bag is sleeved on the semi-finished composite material cover body. Among them, the upper end of the vacuum bag is sealed to the cap 6 and the glue port 7 is exposed, and the lower end of the vacuum bag is sealed to the flange seat 4 and the glue inlet 3 is exposed. After blocking the glue inlet 3 by installing a ball valve at the port of the glue inlet 3, the first vacuum pumping is started by the vacuum pump through the glue outlet 7. After the vacuum reaches -0.098 MPa, keep the pressure for 10 min, and the vacuum degree drop is not more than 0.01 MPa. After the first vacuum pumping is completed, then repeat the above operation, sleeve another vacuum bag outside the vacuum bag, and conduct the second vacuum pumping. After the second vacuum pumping reaches -0.098 MPa, keep the pressure for 10 min, and the vacuum degree drop is not more than 0.01 MPa, then the vacuum degree is qualified. Thus, the compression shaping of the semi-finished composite material cover body is completed.

[0033] After mixing and configuring according to the ratio of vinyl resin:diluent:coupling agent:curing agent:accelerator = 100:3:0.5:2.5:1.2, put it into a vacuum drying oven to evacuate air bubbles for 10 min; reserve for use. The diluent is styrene, the coupling agent is silane coupling agent KH-560, the curing agent is methyl ethyl ketone peroxide, and the accelerator is cobalt isooctanoate.

[0034] Connect the glue outlet 7 of the mold to the vacuum pump, and connect the glue inlet 3 to the container containing the resin through a PTFE tube. Under the condition of a vacuum degree not less than -0.095 MPa, make the resin enter the layering mold under negative pressure and infiltrate the semi-finished composite material cover body upward through the gap between the core mold 5 and the flange seat 4. When the resin is injected from the bottom to the injection port at the first 1 / 3 position, put the injection tube at this position into the resin bucket to continue injecting resin at this position. When the resin is injected from the bottom to the injection port at the second 1 / 3 position, put the injection tube at this position into the resin bucket to continue injecting resin at this position until the injection is finally completed. After the glue outlet 7 discharges glue, close the glue inlet 3, continue to pump vacuum to discharge the excess resin and air bubbles until there are no air bubbles at the glue outlet end, then close the glue outlet 7 and the vacuum pump.

[0035] After closing the glue outlet 7, in order to prevent the vacuum bag from being damaged and leaking due to the movement of the fabric, curing is carried out under normal temperature conditions in place, and the curing time is 24 hours. After curing is completed, the vacuum bag film and the laying mold are removed, the burrs of the composite material cover are polished with sandpaper, and after internal flaw detection is carried out by X-ray, the finished product of the composite material cover is obtained.

[0036] Example 2

[0037] First, disassemble the cover structure diagram, and carry out structural design of the composite material according to the disassembly diagram. The inner layer is designed as a porous structure of a corrosion-resistant vinyl resin composite quartz fiber woven sleeve, and the outer layer is designed as a dense structure of a vinyl resin composite low-density quartz needle felt. It is required that the inner layer has excellent radial mechanical properties and high water pressure resistance, and the dense outer layer structure can ensure the watertightness of the product. The overall material has good wave transmission performance, can meet the requirements of the product for mechanical properties, wave transmission performance and watertightness at the same time, and is designed to be formed by one-time injection molding, so the product integrity is better.

[0038] According to the product structure design, a laying mold is prepared. The laying mold includes a cap 6, a core mold 7, a base 1 and a bottom plate 2. The base 1 is fixedly equipped with the bottom plate 2. A cylindrical core mold 5 is arranged on the bottom plate 2. A cap 6 is arranged on the top of the core mold 5, and a glue outlet 7 is arranged on the cap 6. A positioning block 8 is arranged on the lower surface of the bottom plate 2 corresponding to the core mold 5. A positioning bolt 9 is arranged on the positioning block 8. One end of the positioning bolt 9 passes through the bottom plate 2 and is threadedly connected with the core mold 5, so as to realize the fixation of the core mold 5 on the bottom plate 2. A flange is arranged on the circumference at the bottom end of the core mold 5. A flange seat 4 is arranged on the core mold 5 corresponding to the flange. A glue inlet 3 is arranged on the flange seat 4 in a radially penetrating manner. A stepped hole is arranged on the flange seat 4. The flange seat 4 is connected with the bottom plate 2 through a fixing bolt. The flange seat 4 is in contact connection with the core mold 5 through the cooperation of the stepped hole and the flange, so as to realize the seal between the flange seat 4 and the core mold 5. A sealing ring is arranged between the flange seat 4 and the core mold 5 and the bottom plate 2 to realize the seal between the flange seat 4 and the core mold 5 and the bottom plate 2.

[0039] Laying: Adopt the method of interval lamination, and sequentially sleeve the quartz woven sleeve and the needle felt on the mold to realize laying. First, lay a layer of quartz woven sleeve, and then lay a layer of needle felt, whose shape corresponds to that of the quartz woven sleeve. The quartz woven sleeve and the needle felt are connected by needle punching technology at the joint between the two. Then, use a quartz cloth strip about 50 mm wide to tightly wrap the inner quartz woven sleeve and the needle felt. Lay 5 cycles in sequence according to this method and order. Among them, the thickness of the quartz woven sleeve is 2 mm, the thickness of the needle felt is 0.6 mm, and the overall thickness is 13 mm. After laying is completed, the whole laying is connected by hook sewing to strengthen the interlayer strength and the overall strength; the semi-finished product of the composite material cover is obtained.

[0040] After the semi-finished product of the composite material cover is prepared, a resin injection port is prepared at every 1 / 3 distance in the length direction of the cover using a PTFE tube, a tee joint, and a diversion tube for segmented injection of glue. A vacuum bag is sleeved on the semi-finished product of the composite material cover. Among them, the upper end of the vacuum bag is sealed to the cap 6 and the glue port 7 is exposed, and the lower end of the vacuum bag is sealed to the flange seat 4 and the glue inlet 3 is exposed. After blocking the glue inlet 3 by installing a ball valve at the port of the glue inlet 3, the first vacuum pumping is started by the vacuum pump through the glue outlet 7. After the vacuum pumping reaches -0.098 MPa, the pressure is maintained for 10 min, and the decrease in vacuum degree is not greater than 0.01 MPa. After the first vacuum pumping is completed, then repeat the above operation, sleeve another layer of vacuum bag outside the vacuum bag, and perform the second vacuum pumping. After the second vacuum pumping reaches -0.098 MPa, the pressure is maintained for 10 min, and the decrease in vacuum degree is not greater than 0.01 MPa, then the vacuum degree is qualified; thus, the compression molding of the semi-finished product of the composite material cover is completed.

[0041] After mixing and configuring according to the ratio of vinyl resin: diluent: coupling agent: curing agent: accelerator = 100:3:0.5:2.5:1.2, it is put into a vacuum drying oven for vacuum defoaming for 10 min; reserve for use. The diluent is styrene, the coupling agent is silane coupling agent KH-560, the curing agent is methyl ethyl ketone peroxide, and the accelerator is cobalt isooctanoate.

[0042] Connect the glue outlet 7 of the mold to the vacuum pump, and connect the glue inlet 3 to the container containing the resin through a PTFE tube. Under the condition of a vacuum degree not less than -0.095 MPa, the resin enters the laying mold under negative pressure and infiltrates the semi-finished product of the composite material cover upward through the gap between the core mold 5 and the flange seat 4; when the resin is injected from the bottom up to the injection port at the first 1 / 3 position, the injection tube at this place is put into the resin bucket to make the resin continue to be injected at this place. When the resin is injected from the bottom up to the injection port at the second 1 / 3 position, the injection tube at this place is put into the resin bucket to make the resin continue to be injected at this place until the injection of glue is finally completed. After the glue outlet 7 starts to discharge glue, close the glue inlet 3, continue to pump vacuum to discharge the excess resin and air bubbles until there are no air bubbles at the glue outlet end, and then close the glue outlet 7 and the vacuum pump.

[0043] After closing the glue outlet 7, in order to avoid damage and air leakage of the vacuum bag caused by the movement of the fabric, curing is carried out under the condition of normal temperature in place, and the curing time is 24 h; after the curing is completed, the vacuum bag film and the laying mold are removed, the burrs of the composite material cover are polished with sandpaper, and after internal flaw detection by X-ray, the finished product of the composite material cover is obtained.

[0044] Example 3

[0045] First, disassemble the structure diagram of the cover body, and design the structure of the composite material according to the disassembly diagram. The inner layer is designed as a porous structure of a corrosion-resistant vinyl resin composite quartz fiber woven sleeve, and the outer layer is designed as a dense structure of a vinyl resin composite low-density quartz needle felt. It is required that the inner layer has excellent radial mechanical properties and high water pressure resistance, and the dense outer layer structure can ensure the water tightness of the product. The overall material has good wave transmission performance, can meet the requirements of the product for mechanical properties, wave transmission performance and water tightness at the same time, and is designed to be formed by one-time injection molding, so the product has good integrity;

[0046] According to the product structure design, lay up the mold. The lay-up mold includes a cap 6, a core mold 7, a base 1 and a bottom plate 2. The bottom plate 2 is fixedly installed on the base 1. A cylindrical core mold 5 is arranged on the bottom plate 2. A cap 6 is arranged on the top of the core mold 5, and a glue outlet 7 is arranged on the cap 6. A positioning block 8 is arranged on the lower surface of the bottom plate 2 corresponding to the core mold 5. A positioning bolt 9 is arranged on the positioning block 8. One end of the positioning bolt 9 passes through the bottom plate 2 and is threadedly connected with the core mold 5, so as to fix the core mold 5 on the bottom plate 2; a flange is arranged on the circumference at the bottom end of the core mold 5. A flange seat 4 is arranged on the core mold 5 corresponding to the flange. A glue inlet 3 is arranged on the flange seat 4 in a radially penetrating manner. A stepped hole is arranged on the flange seat 4. The flange seat 4 is connected to the bottom plate 2 through a fixing bolt. The flange seat 4 is in contact connection with the core mold 5 through the cooperation of the stepped hole and the flange, so as to realize the seal between the flange seat 4 and the core mold 5. A sealing ring is arranged between the flange seat 4 and the core mold 5 and the bottom plate 2 to realize the seal between the flange seat 4 and the core mold 5 and the bottom plate 2.

[0047] Lay-up: Adopt the method of interval lamination, and sequentially sleeve the quartz woven sleeve and the needle felt on the mold to realize lay-up. First, lay a layer of quartz woven sleeve, and then lay a layer of needle felt, the shape of which corresponds to that of the quartz woven sleeve. The quartz woven sleeve and the needle felt are connected by needle punching technology at the joint between the two, and then use a quartz cloth tape about 50 mm wide to tightly wrap the inner quartz woven sleeve and the needle felt; lay up 4 cycles in sequence according to this method and sequence. The thickness of the quartz woven sleeve is 2 mm, the thickness of the needle felt is 1.2 mm, and the overall thickness is 12.8 mm. After the lay-up is completed, the whole lay-up is connected by hook sewing to enhance the interlayer strength and the overall strength; obtain a semi-finished product of the composite material cover body;

[0048] After the semi-finished composite material cover is prepared, at every 1 / 3 distance along the length direction of the cover, a resin injection port is prepared using a PTFE tube, a three-way joint, and a diversion tube for segmented injection. A vacuum bag is sleeved on the semi-finished composite material cover. Among them, the upper end of the vacuum bag is sealed to the cap 6 and the glue port 7 is exposed, and the lower end of the vacuum bag is sealed to the flange seat 4 and the glue inlet 3 is exposed. After blocking the glue inlet 3 by installing a ball valve at the port of the glue inlet 3, the first vacuum pumping is started by the vacuum pump through the glue outlet 7. After the vacuum pumping reaches -0.098 MPa, it is pressurized for 10 minutes, and the vacuum degree drops by no more than 0.01 MPa. After the first vacuum pumping is completed, then repeat the above operation, sleeve another layer of vacuum bag outside the vacuum bag, and conduct the second vacuum pumping. After the second vacuum pumping reaches -0.098 MPa, it is pressurized for 10 minutes, and the vacuum degree drops by no more than 0.01 MPa, then the vacuum degree is qualified. Thus, the compression and shaping of the semi-finished composite material cover are completed.

[0049] After mixing and configuring according to the ratio of vinyl resin:diluent:coupling agent:curing agent:accelerator = 100:3:0.5:2.5:1.2, it is put into a vacuum drying oven for vacuum defoaming for 10 minutes; reserve it. The diluent is styrene, the coupling agent is silane coupling agent KH-560, the curing agent is methyl ethyl ketone peroxide, and the accelerator is cobalt isooctanoate.

[0050] Connect the glue outlet 7 of the mold to the vacuum pump, and connect the glue inlet 3 to the container containing resin through a PTFE tube. Under the condition of a vacuum degree not less than -0.095 MPa, make the resin enter the laying mold under negative pressure and infiltrate the semi-finished composite material cover upward through the gap between the core mold 5 and the flange seat 4; when the resin is injected from the bottom to the injection port at the first 1 / 3 position, put the injection tube at this place into the resin bucket to continue injecting resin at this place. When the resin is injected from the bottom to the injection port at the second 1 / 3 position, put the injection tube at this place into the resin bucket to continue injecting resin at this place until the injection is finally completed. After the glue outlet 7 starts to discharge glue, close the glue inlet 3, continue to pump vacuum to discharge the excess resin and air bubbles until there are no air bubbles at the glue outlet end, and then close the glue outlet 7 and the vacuum pump.

[0051] After closing the glue outlet 7, in order to avoid damage and air leakage of the vacuum bag caused by the movement of the fabric, curing is carried out under the condition of normal temperature in place, and the curing time is 24 hours; after curing, remove the vacuum bag film and the laying mold, use sandpaper to polish the burrs of the composite material cover, and conduct internal flaw detection using X-ray, then the finished product of the composite material cover is obtained.

Claims

1. A method for one-time forming of a multi-layer structure resin matrix composite cover body, characterized in that: It includes the following steps: 1). Structural design: First, disassemble the structure diagram of the cover body and conduct structural design on the composite material; 2). Mold design: Design a conformal lay-up mold according to the product structure. Leave a resin inlet and a resin pool at the lower end of the lay-up mold, and leave a resin outlet at the top head position by adding a metal cap to achieve the impregnation process of injecting resin from the bottom and discharging it from the top; 3). Lay-up: Adopt the method of interval lamination to sequentially sleeve the quartz woven sleeve and the needle punched felt on the mold to achieve lay-up. First, lay a layer of quartz woven sleeve, and then lay a layer of needle punched felt, whose shape corresponds to that of the quartz woven sleeve. The quartz woven sleeve and the needle punched felt are connected by needle punching technology at the interface between them. Then, use a quartz cloth tape about 50 mm wide to tightly wrap the inner quartz woven sleeve and the needle punched felt; Lay up 4 - 5 cycles in sequence according to this method and order; After the lay-up is completed, connect the whole lay-up by hook stitching to enhance the interlayer strength and the overall strength; Obtain a semi-finished composite material cover body; 4). Vacuum bag sealing and sizing: After the lay-up is completed, use a PTFE tube, a three-way joint and a diversion tube to prepare a resin injection port at every 1 / 3 distance in the length direction of the cover body for segmented resin injection; Put the vacuum bag on the semi-finished composite material cover body. Among them, seal the upper end of the vacuum bag to the metal cap and expose the resin outlet, and seal the lower end of the vacuum bag to the flange seat and expose the resin inlet. After blocking the resin inlet by installing a ball valve at the resin inlet port, start the first vacuum pumping through the resin outlet by a vacuum pump. After the vacuum pumping reaches -0.098 MPa, keep the pressure for 10 min, and the vacuum degree drops no more than 0.01 MPa; After the first vacuum pumping is completed, then repeat the above operation, put another layer of vacuum bag outside the vacuum bag, and conduct the second vacuum pumping. After the second vacuum pumping reaches -0.098 MPa, keep the pressure for 10 min, and the vacuum degree drops no more than 0.01 MPa, then the vacuum degree is qualified; Thus, complete the compression sizing of the semi-finished composite material cover body; 5). Resin preparation: Mix and configure according to the ratio of vinyl resin: diluent: coupling agent: curing agent: accelerator = 100:3:0.5:2.5:1.2, and then put it into a vacuum drying oven to pump vacuum and defoam for 10 min; Reserve for use; 6). Vacuum resin injection: Connect the resin inlet of the lay-up mold to the container filled with resin through a ball valve and a PTFE tube. Under the condition of a vacuum degree not less than -0.095 MPa, make the resin enter the mold under negative pressure to infiltrate the semi-finished composite material cover body; When the resin is injected from the bottom to the resin injection port at the first 1 / 3 position, put the resin injection tube at this position into the resin bucket to continue resin injection at this position. When the resin is injected from the bottom to the resin injection port at the second 1 / 3 position, put the resin injection tube at this position into the resin bucket to continue resin injection at this position until the resin injection is finally completed; After resin flows out from the resin outlet, close the resin inlet, continue vacuum pumping to discharge the excess resin and air bubbles until there are no air bubbles at the resin outlet end, and then close the resin injection port, the resin outlet and the vacuum pump; 7). Room temperature curing: To avoid damage and air leakage of the vacuum bag caused by fabric movement, curing is carried out under normal temperature conditions in place, and the curing time is 24 hours. After curing is completed, the vacuum bag and the lay-up mold are removed. The burrs of the composite cover are polished with sandpaper, and at the same time, after internal flaw detection of the composite cover using X-rays, the finished product of the composite cover is obtained.

2. The method for one-time forming of a multi-layer structured resin matrix composite cover according to claim 1, characterized in that: The lay-up mold described above includes a cap (6), a core mold (5), a base (1), and a bottom plate (2); the base (1) is fixedly equipped with the bottom plate (2), a cylindrical core mold (5) is arranged on the bottom plate (2), a positioning block (8) is arranged on the lower surface of the bottom plate (2) corresponding to the core mold (5), a positioning bolt (9) is arranged on the positioning block (8), one end of the positioning bolt (9) passes through the bottom plate (2) and is threadedly connected to the core mold (5), a flange is arranged on the circumference at the bottom end of the core mold (5), a flange seat (4) is arranged on the core mold (5) corresponding to the flange, a stepped hole is axially arranged on the flange seat (4), the flange seat (4) is connected to the bottom plate (2) by a fixing bolt, and the flange seat (4) is in contact connection with the core mold (5) through the cooperation of the stepped hole and the flange. A cap (6) is arranged on the top of the core mold (5), and a glue outlet (7) is arranged on the cap (6); a glue inlet (3) is radially penetrated on the flange seat (4).

3. A method for one-time molding of a multi-layer structure resin matrix composite cover according to claim 1, characterized in that: The thickness requirement of the cover product is 10 - 13 mm.

4. A method for one-time forming of a multi-layer structure resin matrix composite cover according to claim 1, characterized in that: The thickness of the quartz woven sleeve is 2 mm, the thickness of the needle-punched felt is 0.2 - 1.2 mm, and the fiber bulk density of the needle-punched felt is 0.2 g / cm 3 .

5. A method for one-step forming of a multi-layer structure resin matrix composite cover according to claim 1, characterized in that: The structure of the middle glue injection port is as follows: First, wind the diversion tube around the cover at about 1 / 3 of the cover length for one week. Both ends of the diversion tube are connected to two interfaces of the tee. The other interface of the tee is connected with a tetrafluoroethylene tube. The tetrafluoroethylene tube is passed through the vacuum bag mold and pulled out. The tetrafluoroethylene tube and the vacuum bag film are sealed with a sealing strip.

6. A method for one-step forming of a multi-layer structure resin matrix composite cover according to claim 1, characterized in that: The diluent described in step 5 is styrene, the coupling agent is silane coupling agent KH-560, the curing agent is methyl ethyl ketone peroxide, and the accelerator is cobalt isooctanoate.

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