A profile-adjusted mold, a profile-adjusted method, and a use method

Abstract

The application discloses a mold for profile adjustment, a profile adjustment method and a use method, and aims to solve the curing deformation problem commonly existing in the composite material forming process. Wherein, through the thinning of the mold plate and the design of the adjustable expansion rod and the free surface deformation technology of the space point cloud, a mold capable of adjusting the profile shape as required is obtained. Meanwhile, the mold plate and the partition plate are lifted, the air flow is reduced, and the temperature uniformity of the mold is improved. Through the simulation analysis technology, the curing deformation amount of the composite material component in the forming is predicted, according to the simulation result, the displacement amount of each expansion rod is calculated by using the reverse node adjustment method, the displacement of the expansion rod is adjusted until the curing deformation amount requirement is met, and the accurate adjustment of the profile is realized. The method can flexibly adjust the mold according to different shapes and sizes of the composite material component, and greatly improves the universality and adaptability of the mold.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mold used for curing of composite materials. BACKGROUND

[0002] In the process of molding of composite materials, curing deformation is an inevitable problem, which has a significant impact on the size, assembly and subsequent processing of the composite materials. In order to effectively inhibit the deformation, the surface compensation is a commonly used method, by setting a certain deformation compensation in the mold design, so that the deformation of the composite materials in the curing process can be offset to a certain extent, so as to ensure the size accuracy of the composite material components.

[0003] However, the traditional surface compensation method faces many challenges in actual operation, one of the biggest problems is that the actual surface change is extremely difficult, which is mainly determined by the inherent form of the mold. The traditional frame mold is composed of multiple partitions and a certain thickness (15mm) of the mold plate, which makes the mold have greater stiffness and strength, but due to the existence of the partition and the thick mold plate, the surface adjustment of the mold becomes relatively complex. The adjustment of the surface needs to be realized by secondary processing (such as milling or additive manufacturing), which not only increases the complexity and cost of the manufacturing process, but also makes it difficult to compensate the surface multiple times

[0004] In the curing process, the composite material is tightly attached to the mold plate for curing, so the accuracy and surface quality of the mold plate have a crucial influence on the molding quality of the composite material components. In order to maximize the molding accuracy of the composite material products and meet the strict size and shape requirements, how to accurately compensate the surface of the mold for the composite material becomes a technical problem to be solved. SUMMARY

[0005] The present application provides a mold for surface adjustment, which can flexibly adjust the surface of the mold.

[0006] The present application also provides a surface adjustment method of the mold, which can accurately adjust the surface of the mold to meet the molding accuracy of the composite material products.

[0007] The present application also provides a use method of the mold, which can prepare the composite material products with high curing molding quality through the mold.

[0008] TECHNICAL SCHEME: In order to achieve the above-mentioned purpose, the present application provides a mold for surface adjustment, which comprises a partition, a plurality of telescopic rods mounted on the partition, and a mold plate supported on the telescopic rods, the mold plate generates a curved surface deformation by adjusting the length of each telescopic rod.

[0009] Beneficial effects: compared with the prior art, the mold plate of the mold with profile adjustment provided by the application can produce curved surface deformation to realize profile compensation.

[0010] The application further provides a mold profile adjustment method, which comprises the following steps of:

[0011] (1) setting a mold simulation model comprising a partition plate profile simulation model and a telescopic rod simulation model, placing the partition plate profile simulation model in a control body of a regular hexahedron, defining a control vertex grid on the control body, and setting the telescopic rod simulation model on the control point;

[0012] (2) moving the control point on the control body to realize deformation of the profile; moving the position of the control point Q i,j,k to obtain a new control point Q i ′ ,j,k ; i, j, k = 0, 1, 2, 3…, when i = j = k = 0, Q i,j,k is the origin of the local coordinate system;

[0013] The Cartesian coordinate system X′ of any point X in the control body is determined by the following formula:

[0014]

[0015] B i,l (s), B j,m (t), B k,n (u) are Bernstein polynomial base functions of the lth, mth and nth degrees respectively;

[0016] Given the profile shape before compensation and the profile shape after compensation, the displacement amount ΔQ i,j,k of each control point is ΔQ i ′ ,j,k -Q i,j,k ;

[0017] Given the profile shape before compensation X(s, t, u) and the profile shape after compensation X′(s, t, u),

[0018] X′(s, t, u) = X(s, t, u) + ΔX(s, t, u)

[0019] ΔX(s, t, u) is the displacement amount of the profile;

[0020]

[0021] According to the profile shape before compensation and the profile shape after compensation, ΔX(s, t, u) is calculated, and then ΔQ i,j,kThe displacement of each control point, i.e. each telescopic rod, is obtained.

[0022] Further, the number and distribution of the telescopic rods are determined by using finite element analysis software, through the geometric shape of the composite product and the expected deformation analysis result.

[0023] Further, the maximum and minimum adjustment range of the telescopic rods are determined according to the predicted curing deformation of the composite material under the worst case.

[0024] Beneficial effects: Compared with the prior art, the mold surface adjustment method provided by the application compensates the mold surface through simulation analysis, so as to obtain the displacement of each telescopic rod, so that the adjusted mold surface shape more accurately compensates the slight deformation of the composite material during the curing process, effectively reduces the dimensional error caused by the deformation of the composite material, and makes the composite material forming precision high.

[0025] The application also provides a use method of the mold: the mold is placed in a hot press tank, the mold is preheated according to the curing temperature requirement of the composite material, the mold surface is compensated, and the compensated mold surface shape is obtained;

[0026] The prepared composite material is laid on the mold surface in a predetermined order and direction, a pressure device is used to apply pressure to the mold, so that the composite material is tightly attached to the mold surface, and at the same time, a heating device inside the mold is used to introduce a heating medium into the mold, so that the composite material is uniformly cured;

[0027] After the composite material is completely cured, the heating device is turned off, and the mold is cooled to room temperature, and in the cooling process, the pressure device continues to maintain a certain pressure on the mold;

[0028] When the mold is cooled to room temperature, the composite material is taken out of the mold. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the mold for mold surface adjustment in the application;

[0030] Figure 2 It is a schematic diagram of the mold surface bending state in the application;

[0031] Figure 3 It is a schematic diagram of the simulation of the mold surface deformation in the finite element software;

[0032] Figure 4 It is a flowchart of the mold surface adjustment method in the application. DETAILED DESCRIPTION

[0033] The technical solutions of the application will be further described below with reference to the drawings.

[0034] Figure 1 and Figure 2 As shown in FIG. 1 and FIG. 2, the mold provided in the present application for profile adjustment includes a partition plate 1, a plurality of telescopic rods 2 mounted on the partition plate 1, and a mold plate 3 carried by the telescopic rods 2, wherein the mold plate 3 is deformed into a curved surface by adjusting the length of each telescopic rod 2. The thickness of the mold plate 3 is controlled to ensure sufficient strength while having a certain flexibility to produce curved surface deformation, for example Figure 2 As shown in FIG. 3, the length of the outer telescopic rod 2 is greater than the length of the inner telescopic rod, so that the two ends of the profile are deformed in a curved manner.

[0035] The telescopic rod can be a commonly used rod that can be accurately controlled, such as a hydraulic rod, a pneumatic rod, an electric cylinder telescopic rod, etc. The specific structure of the telescopic rod is not described here.

[0036] Meanwhile, by reserving a certain gap between the mold plate and the partition plate of the mold to form an overhead structure, the mold plate can reduce the obstruction of hot air flow, so that the hot air is evenly distributed inside the mold, improving the uniformity of the temperature while reducing the energy consumption and production cost of the mold. In the design of the mold plate, the height and gap size of the overhead structure are reasonably determined to ensure that the hot air can flow smoothly under the mold plate, while avoiding excessive deformation or vibration of the mold plate due to suspension.

[0037] Please refer to Figure 3 and Figure 4 For the profile adjustment of the mold plate 3 in the above-mentioned mold, the adjustment displacement amount of each telescopic rod needs to be obtained in advance through simulation analysis.

[0038] Specifically, it includes:

[0039] (1) Set up a mold simulation model including a partition plate profile simulation model and a telescopic rod simulation model. In the setting of the simulation model, the number and distribution of telescopic rods are determined by using finite element analysis software, through the geometric shape of the composite product and the expected deformation analysis results. The number of telescopic rods should be sufficient to capture the geometric characteristics of the product and achieve the required deformation control, and the distribution of telescopic rods should be uniform to ensure that the adjustment of the profile can achieve uniform deformation control on the entire surface of the product. In addition, for each control point, the adjustment capacity of the telescopic rod is evaluated to ensure that it can achieve the required displacement range to compensate for the curing deformation, predict the curing deformation amount of the composite material in the worst case, and determine the maximum and minimum adjustment range of the telescopic rod accordingly.

[0040] Put the partition plate profile simulation model into a control body of a regular hexahedron, and set the telescopic rod simulation model on the control points by defining a control vertex grid on the control body; as shown in Figure 3 .

[0041] By defining a control vertex mesh on the control body, setting the stretchable rods on the control points, and moving the control points on the control body, i.e. the stretchable rods, the deformation of the surface can be realized. The position of the control points of the control body can be expressed by the following formula:

[0042]

[0043] where O' is the origin of the local coordinate system, S, U, T are the axis vectors, and i, j, k = 0, 1, 2, 3…. When i = j = k = 0, Q i,j,k is the origin of the local coordinate system.

[0044] The Cartesian coordinates of any point X in the control body and the local coordinates can be related by the following formula:

[0045]

[0046] where B i,l (s), B j,m (t), and B k,n (u) are Bernstein polynomial basis functions of degrees l, m, and n, respectively, and s, t, u represent the coordinates of the local coordinate system on the control body, which are used to define the position of any point on the surface. The Bernstein polynomial basis function is

[0047]

[0048] where! represents factorial. By moving the position of the control point Q i,j,k , a new control point Q i ' ,j,k can be obtained. After deformation, the Cartesian coordinate system X' of any point X in the control body can be determined by the following formula:

[0049]

[0050] Given the pre-compensation and post-compensation surface shapes, the displacement amount ΔQ i,j,k of each control point = Q i ' ,j,k - Q i,j,k . For example Figure 3 , the displacement amounts ΔQ1 and ΔQ2 of two control points. Given that the pre-compensation surface shape is X(s, t, u) and the post-compensation surface shape is X'(s, t, u), then:

[0051] X'(s, t, u) = X(s, t, u) + ΔX(s, t, u) (5)

[0052] where ΔX(s, t, u) is the displacement of the surface. Combining equations (2), (4) and (5), ΔX(s, t, u) can be expressed as:

[0053]

[0054] To solve ΔQ i,j,k , the above equations are written in matrix form. Let ΔQ be a vector containing the displacement of all control points, B be a matrix containing all Bernstein polynomial basis functions, and ΔX be a vector containing the displacement of all surfaces, then we have:

[0055] ΔX = BΔQ (7)

[0056] By solving this linear equation set, ΔQ can be obtained:

[0057] ΔQ = B -1 ΔX (8)

[0058] where B -1 is the inverse matrix of matrix B. If B is not a square matrix or is not invertible, the least squares method can be used to solve it:

[0059] ΔQ = (B T B) -1 ΔX (9)

[0060] According to the surface shape before and after compensation, ΔX(s, t, u) is calculated, and then ΔQ i,j,k is solved by the above formula, which is the displacement of each control point, i.e. the displacement of the stretching rod, so as to realize the accurate adjustment of the surface.

[0061] After obtaining the displacement data of each control point, the composite material can be cured and formed by a real mold. The use method of the mold is:

[0062] The mold is placed in a hot press tank, preheated according to the curing temperature requirement of the composite material, to ensure that the mold can maintain a stable temperature field during the molding process of the composite material, improve the molding efficiency and quality. The surface of the mold is compensated to obtain the surface shape after compensation.

[0063] The prepared composite material is laid on the surface of the mold in the predetermined order and direction, and the pressure equipment is used to apply pressure to the mold, so that the composite material is tightly attached to the surface, and at the same time, the heating equipment inside the mold is used to introduce the heating medium into the mold, so that the composite material is uniformly cured.

[0064] After the composite material is completely cured, the heating device is turned off and the mold is allowed to cool to room temperature. During the cooling process, the pressure device continues to maintain a certain pressure on the mold to prevent the composite material from deforming due to temperature changes.

[0065] When the mold cools to room temperature, the composite material is removed from the mold. During the removal process, care should be taken to protect the surface of the composite product from scratches or damage. The composite product is inspected for appearance to ensure that the surface is smooth, free of cracks, bubbles, and other defects. A comprehensive quality test is conducted, including size accuracy, shape accuracy, surface quality, and mechanical properties. The composite product is ensured to meet the design requirements. If there is still a deviation from the design requirements, the surface deformation amount is re-determined through the above-mentioned simulation of the surface adjustment method, and the processing is continued until a composite product that meets the design requirements is produced.

[0066] Finally, the composite product is subjected to necessary post-processing, such as removing excess edge material, sanding the surface, and spraying a protective layer, to improve the appearance quality and durability of the composite product.

Claims

1. A method of using a profile-adjustable mold, the mold comprising a partition, a plurality of telescopic rods mounted on the partition, and a mold plate carried by the telescopic rods, the mold plate being capable of being deformed into a curved surface by adjusting the lengths of the telescopic rods, the method comprising the steps of: adjusting the lengths of the telescopic rods to deform the mold plate into a curved surface; and adjusting the lengths of the telescopic rods to deform the mold plate into another curved surface. The mold is put into a hot press tank, the mold is preheated according to the curing temperature requirement of the composite material, the profile of the mold is compensated, and the compensated profile shape is obtained, According to the simulation analysis, the curing deformation is determined, the profile of the mold is compensated according to the node reverse adjustment method, and the compensated profile shape is obtained, which specifically comprises: (1) setting a mold simulation model including a partition plate profile simulation model and an extension rod simulation model, putting the partition plate profile simulation model into a control body of a regular hexahedron, defining a control vertex grid on the control body, and setting the extension rod simulation model on the control point; (2) The control points on the mobile control body realize the deformation of the profile, and the compensated profile shape is obtained ; the profile shape before compensation is known as , profile compensation amount (1); The Cartesian coordinate system of any point X in the control body is determined by the following formula: （2）； wherein, is the position of the control point, when , is the origin of the local coordinate system; are the Bernstein polynomial basis functions of the denotes the coordinates of the local coordinate system on the control volume, which are used to define the position of any point on the profile.​ From formula (1) and formula (2): （3）； Solving for equation (1) and equation (3) , is the compensation amount for the control point; After obtaining the data of each new control point, the operation of curing and forming the composite material by the real mold is carried out; The prepared composite material is laid on the profile of the mold according to the predetermined order and direction, the pressure equipment is used to apply pressure to the mold, so that the composite material is closely attached to the profile, at the same time, the heating equipment inside the mold is used to introduce the heat medium into the mold, so that the composite material is uniformly cured; After the composite material is completely cured, the heating equipment is turned off, and the mold is cooled to room temperature, and the pressure equipment continues to maintain a certain pressure on the mold during the cooling process; When the mold is cooled to room temperature, the composite material is taken out of the mold.

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