A liquid molding VARI process resin infiltration control system and its control method

Abstract

The present invention discloses a resin infiltration control system and its control method for the liquid molding VARI process. The control system includes: a mold, a preform, a fixture group, a vacuum bag group, a glue injection pipeline, a vacuum pumping device, and a semi-permeable membrane. The method includes: First, laying the preform above the mold; Second, laying an auxiliary material layer above the preform; Third, dividing the exhaust channels according to the thickness of the preform perpendicular to the resin infiltration direction, and drilling holes in the glue injection pipeline and the exhaust channels; Fourth, covering the holes of the exhaust channels with a semi-permeable membrane, and placing the glue injection pipeline and the exhaust channels above the auxiliary material; Fifth, performing steps such as sealing. The present invention establishes a "zero glue leakage" system for the composite material VARI process, which can accurately control the resin amount and reduce the resin waste phenomenon. Moreover, it controls the flow front of the resin infiltration process of the variable-thickness reinforcement preform, avoids the problem of air entrainment caused by the convergence of the flow front, and reduces the risk of quality problems such as dry spots and pores in the parts.

Description

Technical Field

[0001] The present invention relates to the technical field of zero-gel VARI process, and more specifically, to a resin infiltration control system and a control method for a liquid molding VARI process. Background Art

[0002] With the continuous development of composite material manufacturing technology, the application of composite materials in the aerospace field is becoming increasingly widespread, and their usage has become an important indicator to measure the advancement of aircraft. Compared with the autoclave molding method, liquid molding technologies represented by VARI (Vacuum Assisted Resin Infusion) have the advantages of low manufacturing cost, high manufacturing efficiency, high dimensional and surface accuracy, etc., and have broad application prospects in composite material molding technologies.

[0003] In the VARI process, a preform is laid on a single-sided core block using carbon fiber, glass fiber, etc. After laying auxiliary materials, resin inlet and outlet channels are laid. Subsequently, the vacuum bag is encapsulated for leak detection, and under the pressure of vacuum conditions, the resin is pressed into the vacuum bag to fully infiltrate the preform. Subsequently, after closing the resin injection and outlet ports, the resin is cured by heating, and after cooling, a composite material part is obtained.

[0004] Resin infiltration process control is one of the key technologies determining the molding quality of the VARI process. Conventional VARI processes require separate injection and outlet pipelines, and the injection and outlet ports on the pipelines are usually set arbitrarily according to experience. The resin flows into the vacuum bag through the injection pipeline to complete the infiltration of the preform, and then the excess resin and the air inside the preform are discharged through the outlet pipeline. In engineering practice, the above resin flow channel setting scheme has the following defects:

[0005] (1) There are differences in the flow rate of the resin in preform areas with different thicknesses, and there are differences in the resin outflow time at each outlet port. It is necessary to manually monitor and control the resin flow situation at each outlet port in real time, and the actual operation process is complicated;

[0006] (2) The differences in the flow rate of the resin in preform areas with different thicknesses cause the flow front to converge inside the preform, enclose gas, and form pores, affecting the molding quality of the part;

[0007] (3) It is difficult to accurately predict the amount of resin flowing out along the outlet port, resulting in difficulty in accurately measuring the resin content inside the preform and inability to achieve precise control of the weight, thickness, etc. of the part, affecting the molding quality of the part;

[0008] (4) There are differences in the resin outflow time at each outlet port, so it is necessary to prepare an excessive amount of resin, resulting in material waste and increased production costs.

[0009] To avoid the above-mentioned defects and optimize the control of the resin infiltration process in the VARI process, those skilled in the art have proposed corresponding solutions. For example, Liu Qiang et al. disclosed a method for manufacturing resin matrix composites by vacuum-assisted resin infiltration with zero resin bleeding (application publication number CN103802331A). This solution eliminates the resin bleeding channel and covers the preform with a semi-permeable membrane material as a whole. Utilizing the property of the semi-permeable membrane material that allows small gas molecules to pass through while blocking large resin molecules, the effect of "zero resin bleeding" in the resin infiltration system can be achieved, thereby simplifying the control of the resin infiltration process, reducing resin waste, and achieving a certain degree of control over the amount of infiltrated resin.

[0010] Although the above solution reduces resin waste, it cannot achieve the control of the resin flow front. This is because the semi-permeable membrane uniformly covers the preform. In the above solution, the pressure is the same in the direction parallel to the injection pipeline, and the driving force for resin infiltration is the same. However, for preforms with variable thickness structures or preform structures with local reinforcement layers, there are differences in the flow resistance of the resin in different regions, which results in different flow rates of the resin in each region. During the infiltration process, the flow fronts in different regions are prone to converge, causing air to be trapped inside the preform, and ultimately resulting in quality defects such as dry spots and pores in the product.

[0011] In terms of regulating the amount of resin infiltration, the solutions in the prior art cancel the resin bleeding channel, so that most of the resin flowing into the vacuum bag is used to infiltrate the preform, achieving a certain degree of control over the amount of resin infiltration. However, in the actual engineering practice, after visually observing that the reinforcement preform is completely infiltrated by the resin, when the infiltration time is extended, the resin infiltration is still proceeding slowly. Generally speaking, the control of the resin flow front and the control of the amount of resin infiltration are still technical difficulties that need to be urgently overcome in the VARI process of composite materials. Summary of the Invention

[0012] To overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a resin infiltration control system and its control method for the liquid molding VARI process, including a resin infiltration control system and a solution including an exhaust channel setting solution and a resin infiltration control method, etc., to achieve the control of the flow front of the variable-thickness reinforcement preform, avoid the problem of air entrapment caused by the convergence of the flow front, reduce the risk of quality problems such as dry spots and pores in the parts. The technical solution provided by the present invention can also achieve precise control of the amount of resin infiltration, thereby effectively controlling the thickness and weight of the parts to obtain ideal product quality and performance.

[0013] The object of the present invention is achieved by the following technical solutions:

[0014] A resin infiltration control system for the liquid molding VARI process, comprising:

[0015] A mold, including a product forming area;

[0016] A preform, including a number of pre-impregnated base layers, disposed within the product forming area of the mold;

[0017] An auxiliary material layer, placed on the preform;

[0018] A fixator, including a first fixator and a second fixator, the first fixator and the second fixator are respectively located on both sides of the preform and fixed to the mold;

[0019] A vacuum bag, covering the preform and the auxiliary material layer, and its two sides are respectively connected to the first fixator and the second fixator; a sealed space is formed within the vacuum bag, and the sealed space is evacuated before and / or during resin impregnation;

[0020] A glue injection pipeline, extending into the sealed space, and glue injection holes are provided on the glue injection pipeline, and the glue injection holes are used to inject resin into the sealed space;

[0021] A vacuum pumping device, including a vacuum pump, an exhaust passage, and a vacuum pumping pipeline, the vacuum pump is communicated with the exhaust passage through the vacuum pumping pipeline; exhaust holes are provided on the exhaust passage;

[0022] A semi-permeable membrane: the outside of the exhaust hole on the exhaust passage is coated with a semi-permeable membrane;

[0023] Determine the installation positions of the glue injection pipeline and the exhaust passage, divide the exhaust passage into regions according to the thickness of the preform perpendicular to the resin impregnation direction, drill holes (glue injection holes and exhaust holes) for the glue injection pipeline and the exhaust passage, the number of glue injection holes on the glue injection pipeline is the same as that of the exhaust holes on the exhaust passage and the positions are opposite; the punching spacing d of the exhaust passage in each region is calculated according to formula (1), where n is the number of layers of reinforcing material in the local region (the number of fiber layers of the preform):

[0024] d = 5 + 200×e 0.305×(1-n) (1);

[0025] Resin flows into the first vacuum bag through the glue injection pipeline and impregnates the preform. During the impregnation process, the air in the first vacuum bag is discharged from the first vacuum bag through the exhaust holes on the exhaust passage.

[0026] As a preferred method, the auxiliary material layer is, from bottom to top, a peelable protective layer, a perforated isolation film, a resin absorption layer, and a diversion layer.

[0027] As a preferred method, the resin absorption layer is one or a combination of two of non-alkali fiberglass cloth or resin absorption felt.

[0028] As a preferred method, a gas guide layer is provided on the outer layer of the first vacuum bag, a second vacuum bag is provided on the outer side of the gas guide layer, the second vacuum bag is connected to a vacuum source, and the second vacuum bag is fixed by a sealing putty.

[0029] As a preferred embodiment, the semi-permeable membrane material is one of the following materials: single-layer or double-layer micro-permeable polytetrafluoroethylene composite fabric, microporous A4000 film, microporous vacuum bag.

[0030] A method for controlling resin infiltration in a liquid molding VARI process includes the following steps:

[0031] Step 1: Place the preform above the mold.

[0032] Step 2: Then place an auxiliary material layer above the preform.

[0033] Step 3: Determine the positions of the glue injection pipeline and the exhaust channel. Divide the exhaust channel into regions according to the thickness of the preform perpendicular to the resin infiltration direction. Drill holes in the glue injection pipeline and the exhaust channel. The drilling spacing d of the exhaust channel in each region is calculated according to formula (1), where n is the number of layers of the local area reinforcement material: where 1 ≤ n ≤ 30, the unit of d is mm, and the value is reserved to one decimal place.

[0034] d = 5 + 200 × e 0.305×(1-n) (1);

[0035] Step 4: Wrap the semi-permeable membrane around the exhaust channel holes, and place the glue injection pipeline and the exhaust channel above the auxiliary material.

[0036] Step 5: Cover the fiber-reinforced preform, the auxiliary material layer, the glue injection pipeline, and the exhaust channel with a first vacuum bag, and seal the side edges of the first vacuum bag with sealing putty.

[0037] Step 6: Close the control valve on the glue injection pipeline, connect the glue injection pipeline to the resin reservoir, close the control valve on the exhaust channel, and connect the exhaust channel to the vacuum source.

[0038] Step 7: Open the control valve on the exhaust channel, evacuate the air in the vacuum bag, open the control valve on the glue injection pipeline, and start resin infiltration.

[0039] Step 8: After a period of time when the resin flow front reaches the position of the exhaust channel, close all control valves to complete resin infiltration.

[0040] As a preferred embodiment, in Step 8, after the resin flow front reaches the position of the exhaust channel, start timing. When the time reaches t, close the control valves of all pipelines. The time t is calculated according to the formula. For a variable-thickness fiber-reinforced preform, the fiber-reinforced preform is divided into n regions according to the thickness perpendicular to the resin infiltration direction. The total length is marked as L, and the length perpendicular to the resin infiltration direction of the nth region is marked as ln. This region of the fiber-reinforced preform contains non-woven fabric a n layers, fabric bn Layer:

[0041]

[0042] The beneficial effects of the present invention are as follows:

[0043] 1. The present invention establishes a "zero bleed" system for the VARI process of composite materials, simplifies the control operation of the resin infiltration process, can accurately control the resin amount, and reduces the resin waste phenomenon;

[0044] 2. The present invention realizes the control of the flow front during the resin infiltration process of the variable-thickness reinforcement preform, avoids the problem of air entrainment caused by the convergence of the flow front, reduces the risks of quality problems such as dry spots and pores in the parts. The semi-permeable membrane covers the bleed pipeline, reducing the usage amount of the semi-permeable membrane. The present invention reduces the usage amount of the one-way breathable membrane and lowers the cost of the one-way breathable membrane; at the same time, due to the reduction of the single-permeable membrane usage, surface inspection can be carried out after making the inner bag, improving the surface quality of the product; during curing, the bleed pipeline can be closed by folding or valves, etc., avoiding the risk of product scrapping caused by the resin penetration of the breathable membrane during the heating and curing process;

[0045] 3. The present invention realizes the precise control of the resin infiltration amount through time control, thereby effectively controlling the thickness and weight of the parts to obtain ideal product quality and performance. Compared with the conventional VARI molding process, it has higher composite material molding quality and production efficiency, does not require the control of the vacuum pressure difference, improves the driving force, and has less control difficulty and lower requirements for the resin flow path layout of the system;

[0046] 4. The fiber volume content of the workpiece can reach more than 56%, with good uniformity, and is simple in actual control and operation. The resin flow rate is controlled through the setting of the injection pipeline, and a time-related model is established to control the thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 Schematic diagram of the relationship between the VARI resin infiltration time and the part thickness of the present invention;

[0049] Figure 2 Schematic diagram of the injection and exhaust settings of the resin infiltration control system for the VARI process of the present invention;

[0050] Figure 3For the rule of the thickness of the reinforcing material preform of the present invention and the resin infiltration rate;

[0051] Figure 4 For the measured value of the thickness of the parts in the embodiments of the present invention;

[0052] Figure 5 For the structural schematic diagram of the resin infiltration control system of the VARI process of the present invention;

[0053] Figure 6 For the schematic diagram of the exhaust pipe and holes;

[0054] Figure 7 For the structural schematic diagram of the fixator;

[0055] Figure 8 For the structural schematic diagram of the fixator connection;

[0056] Figure 9 For the structural schematic diagram of the lower fixing component;

[0057] In the figure, 1 - resin collector, 2 - resin pipe, 3 - first fixator, 4 - glue injection pipeline, 5 - second vacuum bag, 6 - first vacuum bag, 7 - flow guiding layer, 8 - peeling layer, 9 - preform, 10 - exhaust channel, 11 - second fixator, 12 - template, 13 - vacuum pumping pipeline, 14 - vacuum pump, 15 - first control valve, 16 - second control valve, 17 - semi-permeable membrane, 31 - upper fixing component, 311 - first arc winding part, 312 - bundle pipe part, 313 - second arc winding part, 314 - upper tenon, 315 - upper arc part, 32 - lower fixing component, 321 - lower arc part, 322 - lower tenon, 323 - annular groove, 33 - fastening component, 331 - movable member, 34 - pressing rod, 35 - tenon head, 36 - handle. Detailed implementation manners

[0058] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0059] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention. Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0060] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0061] In the present invention, unless otherwise clearly specified and defined, if terms such as "installation", "connection", "connection", "fixation" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] Please refer to Figures 1-6 , the present invention provides a liquid molding VARI process resin infiltration control system. The control system includes a mold 12, a fiber-reinforced preform 9, a sealing putty, an auxiliary material layer, a first vacuum bag 6, a glue injection pipeline 4, an exhaust channel 10, a control valve, a vacuum source, and a resin reservoir. A number of holes are provided on the glue injection pipeline 4 and the exhaust channel 10. A semi-permeable membrane 17 is coated outside the exhaust holes on the exhaust channel 10. Resin flows into the first vacuum bag 6 through the glue injection pipeline 4 and infiltrates the fiber-reinforced preform 9. During the infiltration process, the air in the first vacuum bag 6 is discharged from the first vacuum bag 6 through the exhaust holes on the exhaust channel 10. The thickness of the fiber-reinforced preform 9 varies along the direction of the exhaust channel 10 (see Figure 2 ), and the spacing d of the exhaust holes on the exhaust channel 10 in different thickness regions is calculated according to the following formula, where n is the number of layers of reinforcing materials in the local region:

[0063] d = 5 + 200×e 0.305×(1-n) , where 1 ≤ n ≤ 30, the unit of d is mm, and the value is reserved to one decimal place.

[0064] In a preferred embodiment, the auxiliary material layer includes a peelable protective layer (peel layer 8), a perforated isolation film, a resin absorption layer, and a flow guiding layer 7 from bottom to top ( Figure 5 only the flow guiding layer 7 and the peel layer 8 are shown in

[0065] In a preferred embodiment, the resin absorption layer is one or a combination of two of non-alkali fiberglass cloth or resin absorption felt.

[0066] In a preferred embodiment, a gas guiding layer is provided on the outer layer of the first vacuum bag 6, and a second vacuum bag is provided on the outer side of the gas guiding layer. The second vacuum bag 5 is connected to a vacuum source, and the second vacuum bag 5 is fixed on the template 12 by sealing putty.

[0067] In a preferred embodiment, the material of the semi-permeable membrane 17 is one of the following materials: single-layer or double-layer micro-venting polytetrafluoroethylene composite cloth, microporous A4000 film, and microporous vacuum bag.

[0068] An embodiment of the present invention is as follows:

[0069] The part has a flat plate structure with dimensions of 1.5 m x 0.8 m. There is a strengthening layer in the central area with dimensions of 0.8 m x 0.6 m ( Figure 4 ), the reinforcing material uses 10 layers of carbon fiber fabric ET5284 / CF3031 and 2 layers of carbon fiber non-woven fabric ET5284 / U3160, the local strengthening layer is 5 layers of carbon fiber fabric ET5284 / CF3031, the theoretical thickness of the part is 26.2 mm, the theoretical thickness of the strengthening area is 37.7 mm, and the design requirement for the thickness tolerance is ±8%. The implementation process according to the technical solution of the present invention is as follows:

[0070] Step 1: Place the fiber-reinforced preform 9 above the template 12.

[0071] Step 2: Then lay an auxiliary material layer above the fiber-reinforced preform 9, which are in turn a peelable protective layer, a perforated isolation film, a resin absorption layer, and a flow guiding layer 7. Here, the selected resin absorption layer is alkali-free glass cloth.

[0072] Step 3: Take both sides of the long side of the flat plate as the positions for setting the injection pipe 4 and the exhaust channel 10 respectively. Divide the exhaust channel 10 into regions according to the thickness of the fiber-reinforced preform 9 perpendicular to the resin infiltration direction. Specifically, it is divided into two regions with a theoretical thickness of 26.2 mm and one region with a theoretical thickness of 37.7 mm. Drill holes in the injection pipe 4 and the exhaust channel 10. The hole spacing d of the exhaust channel 10 in each region is calculated according to the following formula, where n is the number of layers of the reinforcing material in the local region. The result shows that the hole spacing of the region with a theoretical thickness of 26.2 mm is 12 mm, and the hole spacing of the region with a theoretical thickness of 37.7 mm is 6.5 mm.

[0073] d = 5 + 200 × e 0.305×(1-n) .

[0074] Step 4: Wrap the semi-permeable membrane 17 around the holes of the exhaust channel 10. Here, the selected semi-permeable membrane 17 is a single-layer micro-venting polytetrafluoroethylene composite cloth. Place the injection pipe 4 and the exhaust channel 10 above the auxiliary material, that is, above the auxiliary material, the injection pipe 4 and the exhaust channel 10 are respectively located on both sides of the preform.

[0075] Step Five: Cover the second vacuum bag 5 outside the fiber-reinforced preform 9, the auxiliary material layer, the injection pipeline 4, and the exhaust channel 10, and use sealing putty to fixedly cover the second vacuum bag 5 on the mold 12.

[0076] Lay a gas guiding layer outside the vacuum bag, cover a second vacuum bag outside the gas guiding layer, connect it to a vacuum source, and fix it on the mold 12 with sealing putty.

[0077] Step Six: Close the control valve on the injection pipeline 4, connect the injection pipeline 4 to the resin reservoir, close the control valve on the exhaust channel 10, and connect the exhaust channel 10 to the vacuum source (vacuum pump 14).

[0078] Step Seven: Open the control valve on the exhaust channel 10 to extract the air inside the vacuum bag, open the control valve on the injection pipeline 4, and start resin infiltration.

[0079] Step Eight: Calculate according to the following formula. According to Figure 4 , L = 1500mm, l1 = 450mm, l2 = 600mm, l3 = 450mm, t = 450 / 1500*(0.875*2 + 1.3*10)*2 + 600 / 1500*(0.875*2 + 1.3*15) = 17.4min. Start timing after the resin flow front reaches the position of the exhaust channel 10, and close all pipeline control valves after 17.4min to complete resin infiltration.

[0080]

[0081] During the implementation of this embodiment, the resin infiltration speed is uniform, there is no situation of the flow front gathering and air entrapment. The surface quality of the cured part is good, the non-destructive testing results meet the design requirements, the thickness uniformity of the part is good, and the deviation meets the design index requirements. The specific data is shown in Table 1:

[0082] Table 1

[0083] Region Peripheral region Reinforcement layer region Measured thickness (average value) (mm) 26.4 38.2 Theoretical thickness (mm) 26.2 37.3 Deviation (%) 0.8％ 2.4％

[0084] The working principle of the present invention is as follows: The VARI process requires a vacuum bag to be covered outside the preform 9 and connected to a vacuum source to form a vacuum environment. The resin flow and infiltration speed of the fiber-reinforced preform 9 are jointly affected by the vacuum driving force and resistance. For a fiber-reinforced preform 9 with variable thickness, the resin infiltration resistance in the thicker area is greater, and the resin flow speed is slower. The resin flow front in the surrounding area with a faster flow rate is prone to gathering and entrapping air, forming defects such as dry spots and pores.

[0085] To solve the above problems, the inventor combined computer simulation and verification tests, and summarized the empirical law of the thickness of the reinforcement preform 9 and the resin infiltration rate. The results are as Figure 3 shown. According to this law, the following formula is obtained: d = 5 + 200×e 0.305×(1-n) . The derivation method is as follows: First, based on engineering experience, the exhaust hole spacing corresponding to a preform of 1 layer of dry fiber is 200 mm. When the number of dry fiber layers increases, the exhaust hole spacing is proportional to the resin penetration rate. Second, a correction coefficient of 5 mm is added according to engineering experience. Based on the above empirical law, the present invention improves the setting method of the exhaust channel 10 of the resin infiltration system on the basis of the existing technology in the field. According to Figure 3 the fitting results in, the exhaust hole setting density of the exhaust pipe in different thickness regions of the fiber-reinforced preform 9 is adjusted to control the resin infiltration driving force, so as to achieve the uniformity of the resin flow front in different thickness regions.

[0086] In terms of regulating the resin infiltration amount, the law of the resin infiltration time and the thickness of the cured part is explored through a large number of experiments. The results are as Figure 1 shown. Within a certain infiltration time range, the part thickness shows an approximately linear trend of increase with the extension of time. After exceeding a certain time range, when the infiltration time is extended, the increase in the part thickness slows down. The present invention uses the above law to summarize the empirical formula for the optimal resin infiltration time of the reinforcement preform 9 to accurately control the resin infiltration time.

[0087] For the fixator, in the traditional technical solution, the vacuum bag is often laid on the template 12 and fixed by the sealing putty. However, during the actual resin infiltration process, the vacuum is pumped in the vacuum bag, stretching the sealing putty. After the sealing putty is damaged, the sealing effect of the vacuum bag is damaged, and air enters the inside of the preform 9, which will also cause quality defects such as dry spots and pores in the product.

[0088] To overcome the above defects, the present invention also provides an embodiment of a sealing structure.

[0089] A sealing structure applied to a resin infiltration control system of the liquid molding VARI process, the fixator (the first fixator 3 and / or the second fixator 11) includes an upper fixing component 31, a lower fixing component 32, and a fastening component 33 connecting the upper fixing component 31 and the lower fixing component 32;

[0090] The fastening assembly 33 is provided on both sides of the upper fixing assembly 31 and the lower fixing assembly 32, and includes a movable member 331 and a fixed member. The fixed member is provided on both sides of the upper fixing assembly 31, and the movable member 331 is provided on both sides of the lower fixing assembly 32. The movable member 331 and the fixed member can be separated or fixed. When the movable member 331 is separated from the fixed member, the upper fixing assembly 31 and the lower fixing assembly 32 are not connected by the fastening assembly 33. When the movable member 331 is fixedly connected to the fixed member, the two sides of the upper fixing assembly 31 and the lower fixing assembly 32 are fixedly connected.

[0091] The upper fixing assembly 31 is provided with a first arc winding portion 311, a tube bundling portion 312 and a second arc winding portion 313. The side of the vacuum bag sequentially passes through the first arc winding portion 311, the tube bundling portion 312 and the second arc winding portion 313 and extends to the lower fixing assembly 32. An upper mortise 314 is provided at the bottom of the upper fixing assembly 31.

[0092] The tube bundling portion 312 is used in cooperation with the pressing rod 34. The vacuum bag passes through the tube bundling portion 312 and is tightly fixed by the pressing rod 34, achieving the effects of sealing and fixing.

[0093] The lower fixing assembly 32 is provided with a lower mortise 322 that matches the upper mortise 314 at its upper part. The upper mortise 314 and the lower mortise 322 cooperate to form an assembling portion, and the assembling portion cooperates with the tenon 35. The tenon 35 connects and fixes the upper fixing assembly 31 and the lower fixing assembly 32. During use, the side of the vacuum bag is placed down to the assembling portion, and the tenon 35 abuts against the vacuum bag and presses the vacuum bag into the assembling portion, achieving the effects of secondary sealing and fixing.

[0094] In summary, the entire fixator includes two - stage fixing structures, namely the fastening assembly 33 and several mortise - tenon structures (the combination of the tenon 35 and the assembling portion). For the sealing and fixing of the side of the vacuum bag, it includes three levels. The first level is the cooperation structure of the tube bundling portion 312 and the pressing rod 34 plus two arc winding portions. The second level is the mortise - tenon structure. The third level is, on the basis of the first and second levels, further sealed and fixed by sealing putty. Generally, the fixators on both sides can be used. In special cases, one fixator is used both front - back and left - right, cooperating with the three - level sealing and fixing structure, ensuring that the enclosed space is not damaged, the product forming quality is good, and external air interference is avoided. In addition, since fixators are used in the direction of the air pressure driving force, the pressure at other positions is relatively small. Therefore, only sealing putty can be used for fixing.

[0095] It should be noted that a handle 36 is configured on the tenon 35, as Figure 8 shown, facilitating the insertion and extraction of the tenon 35.

[0096] When using the fixator, the sealing putty can completely cover the outside of the fixator to achieve the sealing effect.

[0097] Considering the installation of the first vacuum bag 6, as well as the resin injection pipeline 4 and the exhaust passage 10, through holes for pipes are provided on the fixators on both the left and right sides. A part of the through hole for pipes (such as Figure 7 the upper arc portion 315) is provided on the upper fixing assembly 31, and another part (such as Figure 9 the lower arc portion 321) is provided on the lower fixing assembly 32.

[0098] As Figure 9 shown, the resin pipe 2 is a passage for the resin to enter, and is connected to the resin injection pipeline 4. One end of the resin pipe 2 is connected to a resin injection device. A ring groove 323 is provided in the middle of the through hole for pipes. Clamping rings are provided on the resin pipe 2 and the vacuum pumping pipeline 13, and the clamping rings cooperate with the ring groove 323 to prevent the resin pipe 2 and the vacuum pumping pipeline 13 from falling off. Preferably, a sealing rubber ring is provided between the ring groove 323 and the clamping ring. The resin injection device is connected to the resin injection pipeline 4 through a feed pipe. A sealing port is provided on the first vacuum bag 6, and the feed pipe passes through the sealing port and is communicated with the resin injection pipeline 4. The resin injection holes on the resin injection pipeline 4 inject resin into the closed space, and the rest is discharged to the resin collector 1 through the resin pipe 2 for reuse. A first control valve 15 is provided on the pipeline connected to the resin injection pipeline 4 for controlling the resin inlet, and a second control valve 16 is provided on the pipeline connected to the exhaust passage 10 for controlling the vacuum pumping.

[0099] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid molding VARI process resin infiltration control system, characterized in that, Comprising: A template with a product forming area provided thereon; a preform, including a number of pre-infiltrated base layers, disposed within the product forming area of the template; an auxiliary material layer, placed on the preform; a fixator group, including a first fixator and a second fixator, the first fixator and the second fixator being located on both sides of the preform respectively and fixed to the template; a vacuum bag group, including a first vacuum bag and a second vacuum bag, covering the preform and the auxiliary material layer, and its two sides being connected to the first fixator and the second fixator respectively; a sealed space is formed within the vacuum bag, and the sealed space is evacuated before and / or during resin infiltration; a glue injection pipeline, extending into the sealed space, with glue injection holes provided on the glue injection pipeline, and the glue injection holes are used to inject resin into the sealed space; a vacuum pumping device, including a vacuum pump, an exhaust passage, and a vacuum pumping pipeline, the vacuum pump is connected to the exhaust passage through the vacuum pumping pipeline; exhaust holes are provided on the exhaust passage; a semi-permeable membrane: the outside of the exhaust holes on the exhaust passage is coated with a semi-permeable membrane, the positions of the glue injection pipeline and the exhaust passage are determined, the exhaust passage is divided into regions according to the thickness of the preform perpendicular to the resin infiltration direction, the glue injection pipeline and the exhaust passage are punched, the number of glue injection holes on the glue injection pipeline is the same as the number of exhaust holes on the exhaust passage and the positions are opposite; the punching spacing d of the exhaust passage in each region is calculated according to formula (1), where n is the number of layers of reinforcing materials in the local region: （1）； The resin flows into the first vacuum bag through the glue injection pipeline and infiltrates the preform. During the infiltration process, the air in the first vacuum bag is discharged from the first vacuum bag through the exhaust holes on the exhaust passage.

2. The liquid molding VARI process resin infiltration control system according to claim 1, characterized in that: The auxiliary material layer is successively from bottom to top a peelable protective layer, a perforated separator film, a resin absorbent layer, and a flow guiding layer.

3. The liquid molding VARI process resin infiltration control system according to claim 2, characterized in that: The resin absorbent layer is one or a combination of two of alkali-free glass cloth or resin absorbent felt.

4. The liquid molding VARI process resin infiltration control system according to claim 1, characterized in that: A gas guiding layer is provided on the outer layer of the first vacuum bag, a second vacuum bag is provided on the outer side of the gas guiding layer, the second vacuum bag is connected to a vacuum source, and the second vacuum bag is fixed by a sealing putty.

5. The liquid molding VARI process resin infiltration control system according to claim 1, characterized in that: The semi-permeable membrane material is one of the following materials: single-layer or double-layer micro-venting polytetrafluoroethylene composite cloth, microporous A4000 film, microporous vacuum bag.

6. A liquid molding VARI process resin infiltration control method, characterized in that: Including the following steps: Step 1: Lay the preform above the template; Step 2: Then lay the auxiliary material layer above the preform; Step 3: Determine the positions of the glue injection pipeline and the exhaust passage, divide the exhaust passage into regions according to the thickness of the preform perpendicular to the resin infiltration direction, punch the glue injection pipeline and the exhaust passage, and the punching spacing d of the exhaust passage in each region is calculated according to formula 1, where n is the number of layers of reinforcing materials in the local region: where 1 ≤ n ≤ 30 and the unit of d is mm （1）； Step 4: Coat the outside of the exhaust passage holes with a semi-permeable membrane, and place the glue injection pipeline and the exhaust passage above the auxiliary material; Step 5: Cover the first vacuum bag outside the fiber-reinforced preform, the auxiliary material layer, the glue injection pipeline, and the exhaust passage, and seal the side edges of the first vacuum bag with a sealing putty; Step 6: Close the control valve on the glue injection pipeline, connect the glue injection pipeline to the resin storage tank, close the control valve on the exhaust passage, and connect the exhaust passage to the vacuum source; Step 7: Open the control valve on the exhaust passage, extract the air in the vacuum bag, open the control valve on the injection pipe, and start resin infiltration; Step 8: After a period of time when the resin flow front reaches the exhaust passage position, close all the control valves to complete resin infiltration.

7. The liquid molding VARI process resin infiltration control method according to claim 6, characterized in that: After the resin flow front reaches the exhaust passage position in the eighth step, start timing. When the time reaches t, close the control valves of all pipelines. The time t is calculated according to formula (2). For the variable-thickness fiber-reinforced preform, the fiber-reinforced preform is divided into N regions along the thickness perpendicular to the resin infiltration direction. The total length is marked as L, and the length of the nth region perpendicular to the resin infiltration direction is marked as ln. The fiber-reinforced preform (2) in this region contains non-woven fabric a n layers, fabric b n layers: （2）。

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