Short-period and low-cost method for reducing deformation of resin-based composite material product

Abstract

The invention discloses a short-period and low-cost method for reducing the deformation of a resin-based composite material product, which comprises the following steps: (1) preparing a composite material test product through a forming mold, counting the deformation of the composite material test product, and determining the reverse design size of the mold; (2) prepreg cloth is laid on the molded surface of the mold needing to be thickened, a vacuum bag is sealed on the periphery of the prepreg cloth, vacuumizing and pressure applying are conducted, heating and curing are conducted, local thickening is conducted on the molded surface of the mold through the prepreg cloth, the thickening size determined in the step (1) is achieved, and the curing temperature of the prepreg cloth is not lower than the curing temperature of a product; (3) machining is conducted on the molded surface of the mold needing to be thinned, and the thinning size designed in the step (1) is achieved; and (4) the optimized mold is used for forming the composite material product. The optimized mold is used for forming a product, a three-coordinate measuring system is used for detecting the deformation of the product, the displacement is reduced by more than or equal to 80%, and the effect of reducing the deformation of the product is remarkable.

Description

Technical Field

[0001] The present application relates to the technical field of composite material manufacturing, and in particular to a short-cycle, low-cost method for reducing deformation of resin-based composite material products. Background Art

[0002] Composite materials have advantages such as high specific modulus and specific strength, and functional designability, and are widely used in aviation, aerospace, automobiles, ships, etc. Due to performance anisotropy, product curing shrinkage and other reasons, resin-based composite products are prone to deformation after demoulding, which makes subsequent assembly and use difficult, thus affecting product performance and quality.

[0003] When reducing the deformation of resin-based composite products, it is generally necessary to adjust the product structure, optimize the curing system, or improve the mold design based on experience or product trial production, and then conduct trial production and make adjustments based on the trial production results. Adjusting the product structure or optimizing the curing system must be based on the premise that it does not affect the performance and use requirements of the product. The degree and scope of adjustment and optimization are limited, which affects the effect of reducing product deformation; improving mold design and remaking the mold have a long cycle and high cost. Summary of the invention

[0004] The present application provides a short-cycle, low-cost method for reducing deformation of a resin-based composite material product to solve the problems existing in the background technology.

[0005] In a first aspect, a short-cycle, low-cost method for reducing deformation of a resin-based composite product is provided, comprising:

[0006] Step (1), preparing a composite material test product by a molding die, counting the deformation of the composite material test product, and determining the size of the reverse design of the die;

[0007] Step (2), laying prepreg on the mold surface to be thickened, sealing a vacuum bag around the prepreg, evacuating and pressurizing, and heating and curing, so as to locally thicken the mold surface through the prepreg and reach the thickening size determined in step (1), wherein the curing temperature of the prepreg is not lower than the curing temperature of the product;

[0008] Step (3), machining the mold surface to be thinned to achieve the thinning size designed in step (1);

[0009] Step (4), using the optimized mold to form the composite product.

[0010] In combination with the first aspect, in certain implementations of the first aspect, the reverse design of the mold includes thickening the molding mold at positions corresponding to convex deformations of the composite material test article, and thinning the molding mold at positions corresponding to concave deformations of the composite material test article.

[0011] In combination with the first aspect, in certain implementations of the first aspect, dimensions of the reverse design of the mold are determined according to a deformation amount of the composite test article.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the deformation amount of the target position is x, and corresponding to the target position, the composite material test product is convexly deformed facing the first molding mold, and the composite material test product is concavely deformed facing the second molding mold, then the sum of the thickening amount of the first molding mold and the thinning amount of the second molding mold is 1.6x~2.4x.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the deformation amount of the target position is x, and the mold reverse design amount corresponding to the target position is x (1±20%). Corresponding to the target position, if the composite material test article is convexly deformed facing the molding mold, the thickening amount of the molding mold is (1±20%)x; if the composite material test article is concavely deformed facing the molding mold, the thinning amount of the molding mold is (1±20%) of the deformation amount of the target position.

[0014] In combination with the first aspect, in certain implementations of the first aspect, in step (2), the number of layers of prepreg to be laid is calculated based on the size of the mold to be thickened and the single-layer thickness of the prepreg, and machining margin is reserved, and machining is performed after the prepreg is cured to achieve the thickening size determined in step (1).

[0015] In combination with the first aspect, in certain implementations of the first aspect, in step (2), the mold is partially polished to increase the roughness of the mold, thereby reducing the possibility of the cured prepreg falling off the mold.

[0016] In combination with the first aspect, in some implementations of the first aspect, the method further includes:

[0017] By repeating steps (1) to (4), an optimization design iteration of the molding die is achieved, wherein, in step (4) of the nth iteration, the nth composite material test product is molded using the nth optimized die;

[0018] If the target position in the nth composite test product is deformed, an n+1th iteration is performed and starts from step (1), wherein the mold shape designed in the nth iteration step (1) is used as a basis, and the mold reverse design is performed according to the deformation amount of the target position in the nth composite test product;

[0019] If the nth composite test product as a whole meets the design requirements, the optimization design iteration of the molding die is skipped.

[0020] In conjunction with the first aspect, in certain implementations of the first aspect, the composite material article satisfies at least one of the following:

[0021] The reinforcing material used in the resin-based composite material is one or a mixture of two or more of carbon fiber, high silica fiber, quartz fiber, aramid fiber, aramid fiber or polyester fiber, and the structural form is one or a mixture of two or more of needle punching, 2.5D, three-dimensional five-way, orthogonal three-way weaving;

[0022] The resin used in the resin-based composite material is one or a hybrid of two or more of phenolic resin, epoxy resin, bismaleimide resin and polyimide resin;

[0023] The method of forming the composite product is any one of the following: hand lay-up, winding, compression molding, resin transfer molding RTM, vacuum assisted molding and autoclave molding.

[0024] In combination with the first aspect, in certain implementations of the first aspect, the composite material prepreg in step (2) is any one of the following: glass fiber reinforced epoxy resin prepreg, carbon fiber reinforced epoxy resin prepreg and glass fiber reinforced phenolic resin prepreg.

[0025] Compared with the prior art, the solution provided by this application includes at least the following beneficial technical effects:

[0026] (1) The present invention optimizes the size of the molding die based on the statistical data of the deformation of the resin-based composite product: the mold surface corresponding to the concave deformation of the product is reduced by machining; the mold surface corresponding to the convex deformation of the product is increased by hand-laying composite material prepreg cloth-vacuum pressure-heating and curing molding. The above-mentioned mold reverse design is used to offset part of the deformation of the product and reduce the deformation of the product;

[0027] (2) The mold optimization design cycle of the present invention is ≤1 day, the mold hand lay-up filling cycle is ≤2 days, and the mold machining cycle is ≤2 days, and the total cycle is short;

[0028] (3) In the present invention, only the local part of the mold corresponding to the deformation of the product is machined, and the prepreg used for filling is selected according to the curing temperature of the product. The price of the prepreg used for medium-temperature curing products is about 100 to 200 yuan / m 2 , the total cost is controllable;

[0029] (4) The present invention can iterate by repeatedly implementing steps (1) to (4) to ultimately eliminate deformation of the composite material product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of a resin-based composite material product.

[0031] Figure 2It is a cross-sectional view of a resin-based composite product.

[0032] Figure 3 It is a cross-sectional view of a molding die for a resin-based composite product. DETAILED DESCRIPTION

[0033] The present application is further described in detail below in conjunction with specific embodiments.

[0034] The present invention provides a short-cycle, low-cost method for reducing deformation of a resin-based composite material product, the method comprising the following steps:

[0035] Step (1) is to prepare a composite material test product by using a molding die, calculate the deformation amount of the composite material test product, and determine the reverse design size of the die.

[0036] The reverse design of the mold in step (1) means that the molding mold is thickened at the position corresponding to the convex deformation of the composite material test product, and the molding mold is thinned at the position corresponding to the concave deformation of the composite material test product. In this way, the optimized molding mold size can be obtained, and part of the deformation of the product can be offset by the reverse design of the mold.

[0037] Figure 1 to Figure 2 A resin-based composite product is shown. Figure 3 A resin-based composite material product forming mold is shown. In step (1), Figure 3 The molding die shown is used to prepare a composite test product. The deformation of the composite test product is then counted. Specifically, dimensional measurements are performed at several measuring points in the composite test product. If a certain measuring point of the composite test product moves outward, it means that the measuring point is a convex deformation with respect to the outer mold of the molding die, and the measuring point is a concave deformation with respect to the core mold of the molding die; then the reverse design of the mold includes thickening the outer mold of the molding die and thinning the core mold of the molding die. If a certain measuring point of the composite test product moves inward, it means that the measuring point is a concave deformation with respect to the outer mold of the molding die, and the measuring point is a convex deformation with respect to the core mold of the molding die; then the reverse design of the mold includes thinning the outer mold of the molding die and thickening the core mold of the molding die.

[0038] The amount of reverse design of the mold in step (1) can be determined based on the deformation amount of the composite test product.

[0039] In one embodiment, the deformation amount of the target position is x. Corresponding to the target position, the composite material test product is convexly deformed toward the first molding die, and concavely deformed toward the second molding die. Then the sum of the thickening amount of the first molding die and the thinning amount of the second molding die is 1.6x to 2.4x. Combined with the above, if the outward displacement of a certain measurement point of the composite material test product is x, the outer mold thickening amount + the core mold thinning amount = (1±20%) * 2x; if the inward displacement of a certain measurement point of the composite material test product is x, the outer mold thinning amount + the core mold thickening amount = (1±20%) * 2x.

[0040] Further, assuming that the deformation amount of the target position is x, the reverse design amount of the mold corresponding to the target position is x(1±20%). If the composite material test product is deformed convexly toward the molding mold, the thickening amount of the molding mold is (1±20%)x, and if the composite material test product is deformed concavely toward the molding mold, the thinning amount of the molding mold is (1±20%) of the deformation amount of the target position. For example, if the outward displacement of a certain measurement point of the composite material test product is a, the outer mold of the molding mold is thickened by (1±20%)a, and the core mold of the molding mold is thinned by (1±20%)a; if the inward displacement of a certain measurement point of the composite material test product is b, the outer mold of the molding mold is thinned by (1±20%)b, and the core mold of the molding mold is thickened by (1±20%)b.

[0041] Step (2), laying prepreg on the mold surface to be thickened, sealing a vacuum bag around the prepreg, evacuating and pressurizing, and heating and curing, so as to locally thicken the mold surface through the prepreg and reach the thickening size determined in step (1).

[0042] The composite material prepreg for filling the mold is selected according to the curing temperature of the composite material product, and the curing temperature of the prepreg is not lower than the curing temperature of the product. In other words, in order to prevent the state of the prepreg from changing when the product is cured, the curing temperature of the prepreg is not lower than the curing temperature of the product.

[0043] In some embodiments, in step (2), the number of layers of prepreg to be laid can be calculated based on the size of the mold to be thickened and the single-layer thickness of the prepreg, and a machining margin can be reserved. Machining can be performed after the prepreg is cured to achieve the thickening size determined in step (1). Taking the case where a certain measurement point of a material test product moves outward as an example, the mold that needs to be thickened in the molding mold is the outer mold. By laying the prepreg at the position of the outer mold corresponding to the measurement point, the outer mold is locally thickened and filled. In order to reserve a machining margin, the thickness of the laid prepreg can be greater than the thickening size determined in step (1). Therefore, after the prepreg is cured, the mold is machined and repaired so that the mold can be more accurately adjusted to the thickening size determined in step (1).

[0044] In some embodiments, in order to increase the bonding strength between the prepreg and the mold, the mold may be partially polished to increase the roughness of the mold, thereby reducing the possibility of the cured prepreg falling off the mold.

[0045] Step (3), machining the mold surface to be thinned to achieve the thinning size designed in step (1).

[0046] Step (4), using the optimized mold to form a composite product, measuring the product's external dimensions, and verifying the effect of reducing product deformation.

[0047] In some embodiments, in order to prevent the prepreg cloth at the thickened part of the mold from sticking to the composite product, a release cloth may be laid on the surface of the mold.

[0048] In some embodiments, by repeating steps (1) to (4), the optimization design iteration of the molding die is achieved to accurately eliminate the deformation of the composite product.

[0049] For example, in step (4) of the nth iteration, the nth composite test product is formed using the nth optimized mold. If the target position in the nth composite test product is deformed, the n+1th iteration is performed and starts from step (1), wherein the mold shape designed in step (1) of the nth iteration is used as the basis, and the mold reverse design is performed according to the deformation amount of the target position in the nth composite test product. If the nth composite test product as a whole meets the design requirements, the optimization design iteration of the molding mold is skipped.

[0050] In some embodiments, the reinforcing material used in the resin-based composite material is a mixture of one or more of carbon fiber, high silica fiber, quartz fiber, aramid fiber, aramid fiber or polyester fiber, and the structural form is a mixture of one or more of needle punching, 2.5D, three-dimensional five-way, orthogonal three-way weaving.

[0051] In some embodiments, the resin used in the resin-based composite material is one or a hybrid of two or more of phenolic resin, epoxy resin, bismaleimide resin, and polyimide resin.

[0052] In some embodiments, the composite material prepreg in step (2) is a glass fiber reinforced epoxy resin prepreg, a carbon fiber reinforced epoxy resin prepreg or a glass fiber reinforced phenolic resin prepreg.

[0053] In some embodiments, the method of forming the composite article in step (4) is hand lay-up, winding, compression molding, resin transfer molding (RTM), vacuum assisted molding or autoclave molding.

[0054] The present invention is described in detail below in conjunction with specific embodiments, and the embodiments are used to describe the present invention rather than to limit the present invention.

[0055] Example 1

[0056] Figure 1 It is a quartz fiber reinforced phenolic resin composite material product, which is formed by RTM process. Figure 2 From the cross section shown, points 3 to 7 are displaced downward, and points 13 to 17 are displaced upward. The displacement amounts are shown in Table 1.

[0057] Table 1 Displacement of each point of composite products (unit: mm)

[0058] Point 3 4 5 6 7 13 14 15 16 17 Displacement 1.05 1.76 1.98 1.79 1.10 0.93 1.39 1.15 1.32 0.89

[0059] The present invention is used to reduce the deformation of the composite material product, and the specific steps are as follows.

[0060] a) According to the displacement in Table 1, optimize the cavity size of the product molding mold, such as Figure 3 As shown in the figure, the cavity points 3 to 7 are pressed upward, that is, the 3# outer mold in this area is thickened and the core mold is thinned; points 13 to 17 are pressed downward, that is, the 1# and 2# outer molds in this area are thickened and the core mold is thinned. See Table 2 for details.

[0061] Table 2 Optimization scheme of product molding mold

[0062]

[0063] b) The curing temperature of the composite product is 80-85°C. A glass fiber reinforced phenolic resin prepreg cured at 130°C is selected to fill the mold. The single layer thickness of the prepreg is about 0.25 mm.

[0064] c) Sand with 150 grit sandpaper Figure 3 As shown in the 1#, 2#, and 3# outer mold surfaces, 8 layers of prepreg are laid on the 1# and 2# outer mold surfaces respectively, and 12 layers of prepreg are laid on the 3# outer mold surface. A vacuum bag is sealed around the prepreg, and the vacuum is evacuated to ≤-0.095MPa. The prepreg is pressurized and placed in an oven at 130°C for 2 hours. The oven is then turned off and the temperature is naturally lowered. The prepreg is machine-cured according to the optimized outer mold shape to achieve the designed thickening size.

[0065] d) machining the core mold surface according to the optimized core mold shape to achieve the designed thinning size and realize the mold optimization scheme in Table 2;

[0066] e) The optimized mold was used to form the product, and the three-coordinate measurement system was used to detect the deformation of the product. The downward displacement from point 3 to point 7 and the upward displacement from point 13 to point 17 are shown in Table 3. Compared with Table 1, the displacement decreased by ≥80%, and the effect of reducing product deformation was significant.

[0067] Table 3 Displacement of products formed by optimized molds (unit: mm)

[0068] Point 3 4 5 6 7 13 14 15 16 17 Displacement 0.17 0.30 0.13 0.17 0.16 0.14 0.27 0.03 0.25 0.20

[0069] Although the present invention is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A short-cycle, low-cost method for reducing the deformation of resin-based composite products. It is characterized in that include: Step (1), preparing a composite material test product by a molding die, counting the deformation of the composite material test product, and determining the size of the reverse design of the die; Step (2), laying prepreg on the mold surface to be thickened, sealing a vacuum bag around the prepreg, evacuating and pressurizing, and heating and curing, so as to locally thicken the mold surface through the prepreg and reach the thickening size determined in step (1), wherein the curing temperature of the prepreg is not lower than the curing temperature of the product; Step (3), machining the mold surface to be thinned to achieve the thinning size designed in step (1); Step (4), using the optimized mold to form the composite product.

2. The method according to claim 1, It is characterized in that The reverse design of the mold includes thickening the molding mold at the position corresponding to the convex deformation of the composite material test product, and thinning the molding mold at the position corresponding to the concave deformation of the composite material test product.

3. The method according to claim 1, It is characterized in that The dimensions of the reverse design of the mold are determined according to the deformation of the composite test article.

4. The method according to claim 3, It is characterized in that The deformation amount at the target position is x. Corresponding to the target position, the composite material test product is convexly deformed facing the first molding die, and the composite material test product is concavely deformed facing the second molding die. The sum of the thickening amount of the first molding die and the thinning amount of the second molding die is 1.6x~2.4x.

5. The method according to claim 4, It is characterized in that The deformation amount of the target position is x, and the reverse design amount of the mold corresponding to the target position is x (1±20%). Corresponding to the target position, if the composite material test product is convexly deformed facing the molding mold, the thickening amount of the molding mold is (1±20%)x; if the composite material test product is concavely deformed facing the molding mold, the thinning amount of the molding mold is (1±20%) of the deformation amount of the target position.

6. The method according to claim 1, It is characterized in that In step (2), the number of layers of prepreg to be laid is calculated based on the required thickness of the mold and the single-layer thickness of the prepreg, and a machining margin is reserved. Machining is performed after the prepreg is cured to achieve the thickened size determined in step (1).

7. The method according to claim 1, It is characterized in that In step (2), the mold is partially polished to increase the roughness of the mold, thereby reducing the possibility of the cured prepreg falling off the mold.

8. The method according to claim 1, It is characterized in that The method further comprises: By repeating steps (1) to (4), an optimization design iteration of the molding die is achieved, wherein, in step (4) of the nth iteration, the nth composite material test product is molded using the nth optimized die; If the target position in the nth composite test product is deformed, an n+1th iteration is performed and starts from step (1), wherein the mold shape designed in the nth iteration step (1) is used as a basis, and the mold reverse design is performed according to the deformation amount of the target position in the nth composite test product; If the nth composite test product as a whole meets the design requirements, the optimization design iteration of the molding die is skipped.

9. The method according to claim 1, It is characterized in that The composite material product satisfies at least one of the following: The reinforcing material used in the resin-based composite material is one or a mixture of two or more of carbon fiber, high silica fiber, quartz fiber, aramid fiber, aramid fiber or polyester fiber, and the structural form is one or a mixture of two or more of needle punching, 2.5D, three-dimensional five-way, orthogonal three-way weaving; The resin used in the resin-based composite material is one or a hybrid of two or more of phenolic resin, epoxy resin, bismaleimide resin and polyimide resin; The method of forming the composite product is any one of the following: hand lay-up, winding, compression molding, resin transfer molding RTM, vacuum assisted molding and autoclave molding.

10. The method according to claim 1, It is characterized in that The composite material prepreg in step (2) is any one of the following: glass fiber reinforced epoxy resin prepreg, carbon fiber reinforced epoxy resin prepreg and glass fiber reinforced phenolic resin prepreg.

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