Molded surface adjusting mold, molded surface adjusting method and using method

Abstract

The invention discloses a molded surface adjusting mold, a molded surface adjusting method and a using method, and aims to solve the problem of curing deformation generally existing in a composite material forming process. The mold with the molded surface shape capable of being adjusted according to needs is obtained through a thinned plate, a telescopic rod capable of being adjusted and a free-form surface deformation technology of spatial point cloud. And meanwhile, the template and the partition plate are suspended, so that the obstruction of air circulation is reduced, and the temperature uniformity of the mold is improved. According to the method, the curing deformation amount of the composite material component in the forming process is predicted through a simulation analysis technology, the displacement amount of each telescopic rod is calculated through a reverse node adjustment method according to a simulation result, and accurate adjustment of the molded surface is achieved by adjusting the displacement of the telescopic rods till the curing deformation amount requirement is met. By means of the method, the mold can be flexibly adjusted according to the shapes and sizes of different composite material components, and the universality and adaptability of the mold are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of molds used for composite material molding and curing. Background Art

[0002] In the molding process of composite materials, curing deformation is an inevitable problem, which will have a significant impact on the size, assembly and subsequent processing of composite materials. In order to effectively suppress this deformation, surface compensation is a more common method. By pre-setting a certain amount of deformation compensation in the mold design, the deformation of the composite material during the curing process can be offset to a certain extent, thereby ensuring the dimensional accuracy of the composite material components.

[0003] However, traditional surface compensation methods face many challenges in actual operation. One of the biggest problems is that it is extremely difficult to change the actual surface, which is mainly determined by the inherent form of the mold. The traditional frame mold consists of multiple partitions distributed vertically and horizontally and a mold plate of a certain thickness (15mm). This design makes the mold have greater rigidity and strength, but due to the presence of partitions and thick mold plates, the mold surface adjustment becomes relatively complicated. The adjustment of the surface needs to be achieved through secondary processing (such as milling or additive manufacturing), which not only increases the complexity and cost of the manufacturing process, is time-consuming and labor-intensive, but also makes it difficult to compensate the surface multiple times.

[0004] During the curing process, the composite material is cured close to the mold plate, so the accuracy and surface quality of the mold plate have a crucial impact on the molding quality of the composite material component. In order to maximize the molding accuracy of composite products and meet strict size and shape requirements, how to accurately compensate the mold surface of the composite material has become a technical problem that needs to be solved. Summary of the invention

[0005] Purpose of the invention: The present invention provides a mold with adjustable profile, the purpose of which is to be able to flexibly adjust the profile of the mold.

[0006] The present invention also provides a method for adjusting the profile of the mold, the purpose of which is to accurately adjust the profile of the mold to meet the molding accuracy of the product made of the material.

[0007] The invention also provides a method for using the mold, the purpose of which is to use the mold to prepare composite material products with high curing molding quality.

[0008] Technical solution: To achieve the above-mentioned purpose, the present invention provides a mold with adjustable profile, including a partition, a plurality of telescopic rods installed on the partition, and a template supported on the telescopic rods, wherein the template produces 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 present invention can produce curved surface deformation to achieve profile compensation.

[0010] The present invention also provides a method for adjusting the profile of a mold, which determines the amount of solidification deformation according to simulation analysis, and performs profile compensation on the profile of the mold according to a node reverse adjustment method to obtain a compensated profile shape, which specifically includes:

[0011] (1) Setting a mold simulation model including a partition surface simulation model and a telescopic rod simulation model, placing the partition surface simulation model into a regular hexahedron control body, defining a control vertex grid on the control body, and setting the telescopic rod simulation model on the control point;

[0012] (2) Move the control points on the control body to achieve deformation of the surface; by moving the control point Q i,j,k The new control point Q is obtained by 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 volume is determined by the following formula:

[0014]

[0015] B i,l (s),B j,m (t),B k,n (u) are Bernstein polynomial basis functions of degree l, m, and n respectively;

[0016] Given the surface shapes before and after compensation, the displacement of each control point ΔQ i,j,k =Q i ' ,j,k -Q i,j,k ;

[0017] Assume that the shape of the surface before compensation is X(s, t, u), and the shape of the surface after compensation is 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 of the profile;

[0020]

[0021] According to the surface shape before and after compensation, calculate ΔX(s,t,u), and then solve ΔQ by the above formula i,j,k, that is, the displacement of each control point, that is, each telescopic rod.

[0022] Furthermore, the profile of the template is used to lay the composite material, and the number and distribution of the telescopic rods are determined by using finite element analysis software according to the geometric shape and expected deformation analysis results of the composite material product.

[0023] Furthermore, the curing deformation of the composite material under the worst case is predicted, and the maximum and minimum adjustment ranges of the telescopic rod are determined accordingly.

[0024] Beneficial effect: Compared with the prior art, the mold surface adjustment method provided by the present invention performs surface compensation on the mold surface through simulation analysis, thereby obtaining the displacement of each telescopic rod, so that the adjusted surface shape can more accurately compensate for the slight deformation of the composite material during the curing process, effectively reducing the dimensional error caused by the deformation of the composite material and making the composite material molding precision high.

[0025] The present invention also provides a method for using the above mold: the mold is placed in an autoclave, the mold is preheated according to the curing temperature requirement of the composite material, and the mold surface is compensated to obtain a compensated surface shape;

[0026] Lay the prepared composite material on the mold surface in a predetermined order and direction, use a pressure device to apply pressure to the mold to make the composite material fit tightly on the mold surface, and at the same time introduce a heat medium into the mold through a heating device inside the mold to evenly solidify the composite material;

[0027] 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;

[0028] After the mold has cooled to room temperature, the composite material is removed from the mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the structure of the mold for adjusting the mold surface in the present invention;

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

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

[0032] Figure 4 The figure is a flow chart of the profile adjustment method of the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0034] Figure 1 and Figure 2 As shown, the mold for adjusting the profile provided in the present invention comprises a partition 1, a plurality of telescopic rods 2 mounted on the partition 1, and a template 3 supported on the telescopic rods 2. The template 3 generates curved surface deformation by adjusting the length of each telescopic rod 2. By controlling the thickness of the template 3, the template 3 has a certain flexibility while ensuring sufficient strength, so that the curved surface deformation can be generated, for example Figure 2 In the embodiment, the length of the outer telescopic rod 2 is made greater than the length of the inner telescopic rod, so that the two ends of the profile are warped and deformed.

[0035] The telescopic rod may be a commonly used rod that can be precisely controlled, such as a hydraulic rod, a pneumatic rod, an electric cylinder telescopic rod, etc., and the specific structure of the telescopic rod will not be described in detail here.

[0036] At the same time, by leaving a certain gap between the mold plate and the partition of the mold to form an overhead structure, the mold plate can reduce the obstruction of the hot air flow, so that the hot air is evenly distributed inside the mold, improving the temperature uniformity while reducing the energy consumption and production cost of the mold. In the design of the mold plate, the overhead height and gap size 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 combine Figure 3 and Figure 4 As shown, for the profile adjustment of the mold plate 3, it is necessary to obtain the adjustment displacement of each telescopic rod in advance through simulation analysis.

[0038] Specifically include:

[0039] (1) A mold simulation model including a partition profile simulation model and a telescopic rod simulation model is set up. In the setting of the simulation model, the number and distribution of telescopic rods are determined by using finite element analysis software based on 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 features of the product and achieve the required deformation control. At the same time, the distribution of the telescopic rods should be uniform to ensure that the adjustment of the profile can achieve uniform deformation control on the entire product surface. In addition, for each control point, the adjustment ability of the telescopic rods is evaluated to ensure that they can achieve the required displacement range to compensate for the curing deformation, predict the curing deformation of the composite material under the worst case, and determine the maximum and minimum adjustment range of the telescopic rods accordingly.

[0040] The partition surface simulation model is placed in a regular hexahedron control volume, and the telescopic rod simulation model is set on the control point by defining the control vertex grid on the control volume; Figure 3 shown.

[0041] By defining a control vertex grid on the control body, setting the telescopic rod on the control point, and moving the control point on the control body, i.e. the telescopic rod, the deformation of the surface can be achieved. The control point position of the control body can be expressed by the following formula:

[0042]

[0043] Among them, O' is the origin of the local coordinate system, S, U, T are axis vectors, 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 volume can be related to the local coordinates by the following formula:

[0045]

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

[0047]

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

[0049]

[0050] Given the surface shapes before and after compensation, the displacement of each control point ΔQ i,j,k =Q i ' ,j,k -Q i,j,k .For example Figure 3 The displacements of the two control points in are ΔQ1 and ΔQ2. Assume that the shape of the surface before compensation is X(s, t, u) and the shape of the surface after compensation is X′(s, t, u), then:

[0051] X′(s,t,u)=X(s,t,u)+ΔX(s,t,u) (5)

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

[0053]

[0054] To solve for ΔQ i,j,k , write the above equations in matrix form. Let ΔQ be a vector containing the displacements of all control points, B be a matrix containing all Bernstein polynomial basis functions, and ΔX be a vector containing all surface displacements, then:

[0055] ΔX=BΔQ(7)

[0056] By solving this linear system of equations, we can obtain ΔQ:

[0057] ΔQ=B -1 ΔX(8)

[0058] Among them, 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, calculate ΔX(s,t,u), and then solve ΔQ by the above formula i,j,k , that is, the displacement of each control point, that is, the telescopic rod, so as to achieve precise adjustment of the profile.

[0061] After obtaining the displacement data of each control point, the composite material can be cured and molded through the real mold. The method of using the mold is as follows:

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

[0063] Lay the prepared composite material on the mold surface in a predetermined order and direction, use pressure equipment to apply pressure to the mold so that the composite material fits tightly on the mold surface, and at the same time introduce heat medium into the mold through the heating equipment inside the mold to evenly cure the composite material.

[0064] After the composite material is completely solidified, the heating equipment is turned off and the mold is allowed to cool to room temperature. During the cooling process, the pressure equipment 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, remove the composite material from the mold. During the removal process, pay attention to protecting the surface of the composite product to avoid scratches or damage. Perform an appearance inspection on the composite product to ensure that the surface is smooth, free of cracks, bubbles and other defects, and then conduct a comprehensive quality inspection, including dimensional accuracy, shape accuracy, surface quality and mechanical properties. Ensure that the composite product meets the design requirements. If there is still a deviation from the design requirements, re-determine the deformation of the surface through the above-mentioned simulation surface adjustment method, and return to continue processing until a composite product that meets the design requirements is produced.

[0066] Finally, the composite products are subjected to necessary post-processing, such as removing excess edge materials, grinding the surface, spraying a protective layer, etc., to improve the appearance quality and durability of the composite products.

Claims

1. A mold with profile adjustment, characterized in that: The utility model comprises a partition, a plurality of telescopic rods installed on the partition, and a template supported on the telescopic rods. The template generates curved surface deformation by adjusting the length of each telescopic rod.

2. A method for adjusting the mold surface according to claim 1, characterized in that: The curing deformation is determined based on the simulation analysis, and the mold surface is compensated based on the node reverse adjustment method to obtain the compensated surface shape, which specifically includes: (1) Setting a mold simulation model including a partition surface simulation model and a telescopic rod simulation model, placing the partition surface simulation model into a regular hexahedron control body, defining a control vertex grid on the control body, and setting the telescopic rod simulation model on the control point; (2) Move the control points on the control body to achieve deformation of the surface; by moving the control point Q i,j,k The new control point Q is obtained by 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; The Cartesian coordinate system X′ of any point X in the control volume is determined by the following formula: B i,l (s),B j,m (t),B k,n (u) are the Bernstein polynomial basis functions of order l, m, and n respectively; s, t, and u represent the coordinates of the local coordinate system on the control volume, which are used to define the position of any point on the surface; Given the profile shape before and after compensation, the displacement of each control point ΔQ i,j,k =Q i ' ,j,k -Q i,j,k ; Assume that the shape of the surface before compensation is X(s, t, u), and the shape of the surface after compensation is X′(s, t, u). X′(s,t,u)=X(s,t,u)+ΔX(s,t,u) ΔX(s,t,u) is the displacement of the profile; According to the surface shape before and after compensation, calculate ΔX(s,t,u), and then solve ΔQ by the above formula i,j,k , that is, the displacement of each control point, that is, each telescopic rod.

3. The method for adjusting the mold surface according to claim 2, characterized in that: The molded surface of the mold plate is used for laying composite materials, and the number and distribution of telescopic rods are determined by using finite element analysis software according to the geometric shape of the composite material product and the expected deformation analysis results.

4. The method for adjusting the mold surface according to claim 3, characterized in that: The worst-case curing deformation of the composite material is predicted, and the maximum and minimum adjustment ranges of the telescopic rod are determined accordingly.

5. A method for using the mold according to claim 1, characterized in that: The mold is placed in an autoclave, and according to the curing temperature requirements of the composite material, the mold is preheated, and the mold surface is compensated to obtain the compensated surface shape; Lay the prepared composite material on the mold surface in a predetermined order and direction, use a pressure device to apply pressure to the mold to make the composite material fit tightly on the mold surface, and at the same time introduce a heat medium into the mold through a heating device inside the mold to evenly solidify the composite material; After the composite material is completely solidified, 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; After the mold has cooled to room temperature, the composite material is removed from the mold.

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