3D printing composite forming mold and manufacturing method thereof

Abstract

The application discloses a 3D printing composite forming die and a manufacturing method thereof, and comprises a composite base, a base and a Z-direction limiting structure; the top surface of the composite base is a forming surface; the base is connected to the bottom of the composite base; the Z-direction limiting structure is arranged between the composite base and the base, and is used for limiting the Z-direction displacement of the composite base under a high-temperature working condition, and has the advantages of reducing the warping deformation of the die under the influence of the high-temperature working condition and improving the forming quality.

Description

Technical Field

[0001] This application relates to the field of 3D printing mold technology, and in particular to a 3D printing composite molding mold and its manufacturing method. Background Technology

[0002] Carbon fiber reinforced resin matrix composite body panels have a higher specific strength than metal body panels, which is extremely beneficial for the lightweight design and manufacturing of aircraft. Therefore, they are widely used in the production of aircraft body panels both domestically and internationally. To achieve rapid and low-cost manufacturing of body panels, thermoplastic 3D printing is typically used to print the molding die for the composite body panel, and the body panel is then cured and molded on the molding die.

[0003] These molding dies only require thermoplastic composite 3D printing plus simple machining and joining processes, ensuring rapid manufacturing of composite molds for aircraft manufacturing. However, due to the significant anisotropy of the thermal expansion coefficient of existing thermoplastic composite 3D printing materials, the composite molding dies manufactured using this process are relatively weak in rigidity. Under high-temperature conditions, the difference in thermal expansion in different directions generates internal stress. Combined with the overall weak rigidity of the mold, it is highly susceptible to warping deformation, thus affecting the molding accuracy and quality of the parts. Summary of the Invention

[0004] The main purpose of this application is to provide a 3D printed composite molding die and its manufacturing method, which aims to solve the technical problem that existing composite molding dies are easily affected by high temperature working conditions and thus warp and deform.

[0005] To achieve the above objectives, this application provides a 3D printed composite molding die, including a composite substrate, a base, and a Z-direction confinement structure: the top surface of the composite substrate is the molding surface; the base is connected to the bottom of the composite substrate; the Z-direction confinement structure is disposed between the composite substrate and the base, and the Z-direction confinement structure is used to restrict the Z-direction displacement of the composite substrate under high temperature conditions.

[0006] Optionally, the Z-direction limiting structure includes multiple first oblong holes, multiple second oblong holes, and multiple connectors. The multiple first oblong holes are formed on the base; the multiple second oblong holes are formed at the bottom of the composite substrate, and the positions of the second oblong holes correspond one-to-one with the positions of the first oblong holes; the connectors pass through the center positions of the first oblong holes and the corresponding second oblong holes to connect the base to the bottom of the composite substrate.

[0007] Optionally, the center positions of the second oblong hole and the first oblong hole correspond to each other, and the length directions of the second oblong hole and the first oblong hole are perpendicular to each other.

[0008] Optionally, the base includes a square steel frame, multiple reference blocks and a reference plate; the multiple reference blocks are connected to the bottom of the square steel frame; the reference plate is connected to the top surface of the square steel frame, and multiple first waist-shaped holes are all opened through the reference plate.

[0009] Optionally, the composite matrix includes a main frame and a supporting lattice. The top surface of the main frame is the forming surface, and multiple second waist-shaped holes are opened at the bottom of the main frame. The supporting lattice is disposed within the main frame.

[0010] Optionally, the molding surface of the main frame is provided with a high-temperature resistant gel coat layer.

[0011] Optionally, the supporting lattice is a wave-shaped supporting structure.

[0012] To achieve the above objectives, this application also provides a manufacturing method for manufacturing the aforementioned 3D printed composite molding die, comprising the following steps: A composite matrix blank is 3D printed using thermoplastic composite materials and then rough-machined to obtain the composite matrix. Select the corresponding universal metal base from the standard module library according to the design specifications; The rough-machined composite substrate is combined with a general-purpose metal base using connectors to produce an assembly. The assembly is subjected to aging heat treatment according to the aging heat treatment parameters of the thermoplastic composite material used to remove internal stress in the assembly; A molding surface is precision machined on the top surface of the composite substrate of the assembly; wherein, the molding surface is a curved surface; Clean the molding surface thoroughly, and then evenly spray a high-temperature resistant gel coat onto the molding surface area to form a high-temperature resistant gel coat layer.

[0013] Optionally, a composite matrix blank is 3D printed using a thermoplastic composite material and then rough-machined to obtain the composite matrix, including the following steps: A composite matrix blank was printed using a thermoplastic composite 3D printing device; After using a CNC machining center or measuring equipment to check that the allowance on the lower die side of the composite substrate blank is uniform, the connecting surface at the bottom of the composite substrate blank is machined flat, and multiple second waist-shaped holes are machined to obtain the composite substrate.

[0014] Optionally, after forming the high-temperature resistant gel coat layer, the following steps are also included: The surface of the high-temperature resistant gel coat layer was measured using a coordinate measuring machine.

[0015] The beneficial effects that this application can achieve are as follows: When the mold of this application is in use, the composite substrate expands under high temperature. Due to the setting of the Z-direction restriction structure, the Z-direction displacement of the composite substrate under high temperature working conditions is restricted, so that the composite substrate can only move relative to each other in the horizontal direction. This ensures that the overall forming surface of the mold will not warp or deform due to the different thermal expansion in each direction, thereby improving the forming quality of the product when the mold is used. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1 This is a schematic diagram of the structure of a 3D printing composite molding die in an embodiment of this application; Figure 2 This is a schematic diagram of the internal structure of the composite matrix in an embodiment of this application; Figure 3 This is a schematic diagram of the base structure in an embodiment of this application.

[0018] Figure label: 100-Composite substrate, 110-Main frame, 111-Second waist-shaped hole, 120-Supporting lattice, 200-Base, 210-Square steel skeleton, 220-Reference block, 230-Reference plate, 231-First waist-shaped hole, 300-Connector, 400-High temperature resistant gel coat layer.

[0019] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0024] Example 1 Reference Figures 1-3 This embodiment provides a 3D printed composite molding die, including a composite substrate 100, a base 200, and a Z-direction limiting structure: the top surface of the composite substrate 100 is the molding surface; the base 200 is connected to the bottom of the composite substrate 100; the Z-direction limiting structure is disposed between the composite substrate 100 and the base 200, and the Z-direction limiting structure is used to limit the Z-direction displacement of the composite substrate 100 under high temperature conditions.

[0025] In existing technologies, such as the patent titled "A Method for Manufacturing Multi-Surface 3D Printed Composite Material Molding Mold," a mold blank is printed using 3D printing technology, and then CNC precision machining is performed to obtain the finished mold. A special lattice corresponding to the surface is designed to provide support for the multi-surface mold. The mold surface and the supporting lattice are combined through one or more methods such as bonding, metal bolts, tenon and mortise structures, and 3D printing. Such molds only require thermoplastic composite 3D printing plus simple machining and connection processes. However, the thermoplastic composite 3D printing material has a significant anisotropy in the coefficient of thermal expansion. The composite molding mold manufactured using this process has relatively weak rigidity. Under high-temperature conditions, the amount of thermal expansion in each direction of the mold differs greatly, generating internal stress. In addition, the overall rigidity of the mold is weak, making it prone to warping deformation, which affects the molding accuracy and molding effect of the parts.

[0026] Therefore, in this embodiment, when the composite substrate 100 is used, it expands under high temperature. Due to the setting of the Z-direction limiting structure, the Z-direction displacement (i.e., vertical displacement) of the composite substrate 100 under high temperature working conditions is limited, so that the composite substrate 100 can only move relative to each other in the horizontal direction. This ensures that the overall forming surface of the mold will not warp or deform due to the different thermal expansion in each direction, thereby improving the forming quality of the product when the mold is used.

[0027] It should be noted that the composite substrate 100 here is a thermoplastic composite 3D printing substrate.

[0028] As an optional implementation, the Z-direction limiting structure includes a plurality of first oblong holes 231, a plurality of second oblong holes 111, and a plurality of connectors 300. The plurality of first oblong holes 231 are formed on the base 200; the plurality of second oblong holes 111 are formed at the bottom of the composite substrate 100, and the positions of the second oblong holes 111 and the first oblong holes 231 correspond one-to-one; the connectors 300 pass through the center positions of the first oblong holes 231 and the corresponding second oblong holes 111 to connect the base 200 to the bottom of the composite substrate 100.

[0029] In this embodiment, the first oblong hole 231 and the second oblong hole 111 not only serve to connect the base 200 and the composite substrate 100 together with the connecting piece 300 (which may be a bolt), but also, since the first oblong hole 231 and the second oblong hole 111 have a certain length, when the composite substrate 100 is heated and expands at high temperature, the relative movement of the composite substrate 100 in the horizontal direction is released, while the Z-direction displacement is restricted by the connecting piece 300. Ultimately, the molding surface as a whole will not warp or deform due to the different thermal expansion in each direction.

[0030] As an optional implementation, the center positions of the second oblong hole 111 and the first oblong hole 231 correspond to each other, and the length directions of the second oblong hole 111 and the first oblong hole 231 are perpendicular to each other. This allows the composite substrate 100 to have the ability to displace horizontally in the X and / or Y directions when it expands due to heat, depending on its local or overall stress direction. This better adapts to stress changes, especially local stress changes, thus accommodating the anisotropy of the thermal expansion coefficient of the thermoplastic composite 3D printing material. This reduces the deformation of the 3D printing mold during use and improves the product forming accuracy.

[0031] It should be noted that multiple first waist-shaped holes 231 are arranged along their length in both the X and Y directions, which further improves the connection stability and also improves the stability of the composite substrate when it is horizontally displaced by 100.

[0032] As an optional implementation, the base 200 includes a square steel frame 210, a plurality of reference blocks 220 and a reference plate 230; the plurality of reference blocks 220 are connected to the bottom of the square steel frame 210; the reference plate 230 is connected to the top surface of the square steel frame 210, and a plurality of first waist-shaped holes 231 are all opened through the reference plate 230.

[0033] In this embodiment, the square steel frame 210 is a typical welded structure, serving as the main structure of the base 200. The reference block 220 is a metal CNC control unit, welded below the square steel frame 210 and CNC machined to ensure that the base 200 can be placed flat on the ground. The reference plate 230 is a metal flat plate, fully welded to the square steel frame 210 and then machined flat to ensure that the composite substrate 100 can be placed flat on the reference plate 230. First oblong holes 231 in the X and Y directions are provided at regular intervals on the reference plate 230. Simultaneously, second oblong holes 111 are provided at the same positions on the bottom of the composite substrate 100. Bolts and other connecting parts 300 are used to tighten the connection, thereby achieving the connection between the base 200 and the composite substrate 100.

[0034] It should be noted that the base 200 can be designed as a series of standard modules to form a universal metal base 200 to meet the support requirements of one or more composite substrates 100 of different sizes. As an optional implementation, the composite substrate 100 includes a main frame 110 and a support lattice 120. The top surface of the main frame 110 is a molding surface, and a plurality of second waist-shaped holes 111 are opened at the bottom of the main frame 110. The support lattice 120 is disposed within the main frame 110.

[0035] In this embodiment, the main frame 110 is an integral square box structure, with its top surface aligned with the curved surface of the required molded cover part, serving as the molding surface. The other three surfaces are mutually perpendicular planes, facilitating mold placement and processing. The supporting lattice 120 primarily serves to provide support and rigidity. The supporting lattice 120 and the main frame 110 are typically integrally molded using 3D printing (the printing start and end positions are as follows). Figure 2 (As shown).

[0036] As an optional implementation, the molding surface of the main frame 110 is provided with a high-temperature resistant gel coat layer 400. Here, the high-temperature resistant gel coat layer 400 is a continuous and dense surface reinforcement coating with a uniform thickness of 1 mm. It is formed on the molding surface of the main frame 110 by high-temperature spraying and curing to ensure the airtightness of the mold molding surface.

[0037] As an optional implementation, the support lattice 120 is a wave-shaped support structure, which provides good support and stiffness in the middle of the main frame 110 to reduce the risk of deformation of the molding surface.

[0038] In summary, the advantages of the mold in this application are as follows: by combining a 3D printed thermoplastic composite substrate with a universal metal base, the overall rigidity of the 3D printed thermoplastic composite cover mold is improved, while the Z-axis displacement is restricted, reducing the overall deformation of the mold during use, and solving the problem of poor molding effect of existing 3D printed thermoplastic composite mold products.

[0039] Example 2 To achieve the above objectives, this embodiment also provides a design method for designing a 3D printing composite molding die, comprising the following steps: Step S1: Create a reference plane: Extract the maximum outer boundary of the part and select the position of its maximum contour point to create a reference plane. Usually, four contour points at the four corners are selected. Step S2: Creation of the 3D printed composite substrate (i.e., the abbreviation for 3D printed thermoplastic composite substrate) profile segmentation surface: Extract the part's molding surface profile, and use the CATIA surface modeling extrapolation extension command to enlarge the shape of the part's molding surface, usually extending it by 150~200mm along the maximum shape. Offset the extended part's molding surface by 1mm along the molding direction and its normal direction as the profile segmentation surface. Step S3: Creating the maximum outline of the 3D printed composite substrate: Using the reference plane generated in step S1 as the sketch plane, draw the outer dimensions of the mold. Figure 1 ,Grass Figure 1 For example, the maximum external dimensions of the part are approximately 120mm, with rectangular boundaries and length and width directions respectively. (The text also mentions grass, but this seems unrelated to the main point about the part.) Figure 1 Round the rectangle's boundary to an integer. Step S4: Creation of the 3D Printed Composite Matrix: Based on the grass generated in step S3 Figure 1 Stretch the bosses on both sides of the reference plane, with a stretching distance of about 300mm; Step S5: Creation of the 3D printing composite substrate molding surface: Use the profile cutting surface generated in step S2 to divide the extrusion boss generated in step S4. The division direction should be the part molding direction. Step S6: Shelling of 3D Printed Composite Substrate: The segmented mold body is shelled. To avoid excessive printing height during printing, the shell is generally removed along the width of the mold, that is, the shell thickness of the upper, lower, left and right sides of the mold body is retained to the width of a single layer for 3D printing, which is generally 16mm. After shelling, the thickness of the inner side of the mold surface is reduced by 4mm. In actual printing and manufacturing, the thickness of the curved surface of the mold surface is increased by 4mm to be consistent with the thickness of other positions. The 4mm increase here is used as the machining allowance after printing. Step S7: 3D Printing Composite Matrix Reinforcement: Divide the mold cavity after shelling into several equal-spaced frames of approximately 300mm along the mold length. Reinforce each frame, ensuring all frame ribs are continuous. The general principle of reinforcement is that, except for the printing start and end points, the contact points between the reinforcing ribs and the outer frame are designed to be linear to reduce internal stress during printing. The printing start and end points are the starting and ending points of each layer. The printing start and end points should include all elements on the printing cross-section of each layer, and the start and end points can be interchanged, i.e., the starting point of the nth layer is the ending point of the (n+1)th layer, to ensure continuous printing and improve printing efficiency. Step S8: Selection of universal metal base: Based on the maximum shape of the mold generated in step S3, select a universal metal base with a basically matching shape. The general principle for selection is that the maximum shape of the universal metal base should be greater than or equal to the maximum shape of the mold generated in step S3. Step S9: Assemble the 3D printed composite substrate with the universal metal base: Assemble the 3D printed composite substrate and the universal metal base together using the assembly command. The general principle is to keep the position of the 3D printed composite substrate unchanged in the initial modeling coordinate system. Move the universal metal base so that the upper surface of the reference plate of the universal metal base fits against the 3D printed composite substrate. The 3D printed composite substrate is placed in the center on the universal metal base. Step S10: 3D printing composite substrate connection hole creation: Using the connection hole position (i.e. the first waist-shaped hole) on the metal universal base as the opening reference, keep the opening center position consistent, so that the second waist-shaped hole of the 3D printing composite substrate intersects and is perpendicular to the length direction of the first waist-shaped hole on the metal universal base, thus completing the 3D printing composite substrate design. Step S11: High-temperature resistant gel coat layer shape design: based on the grass generated in step S3 Figure 1 The sheet body is stretched to the rectangular boundary and then offset inward by 30mm to form the outer cutting surface of the high-temperature gel coat. Step S12: Cutting the high-temperature resistant gelcoat sheet: Cut the surface segmentation surface obtained in step S2 using the outer cutting surface of the high-temperature resistant gelcoat, and retain the inner curved surface sheet of the cutting surface, which is the high-temperature resistant gelcoat sheet. Step S13: Based on the high-temperature resistant gelcoat sheet, use the thick surface function of the modeling tool to thicken the inner side of the tooling molding surface by 1mm to complete the design of the high-temperature resistant gelcoat layer.

[0040] Example 3 Reference Figures 1-3 To achieve the above objectives, this embodiment also provides a manufacturing method for manufacturing the aforementioned 3D printing composite molding die, comprising the following steps: A composite matrix 100 blank was 3D printed using thermoplastic composite material and then rough-machined to obtain the composite matrix 100. Select the corresponding universal metal base 200 from the standard module library according to the design specifications; The rough-machined composite substrate 100 is combined with the metal general-purpose base 200 using connectors 300 to obtain the assembly; The assembly is subjected to aging heat treatment according to the aging heat treatment parameters of the thermoplastic composite material used to remove internal stress in the assembly; A molding surface is precision machined on the top surface of the composite substrate 100 of the assembly; wherein, the molding surface is a curved surface; Clean the molding surface thoroughly, and then evenly spray a high-temperature resistant gel coat onto the molding surface area to form a high-temperature resistant gel coat layer of 400.

[0041] In this embodiment, the mold is made of a composite substrate 100 produced by thermoplastic composite 3D printing process and combined with a universal metal base 200. The material is lightweight and easy to use. The universal metal base 200 is a series of standard modules, which can realize the preparation of materials in advance. The composite substrate 100 is manufactured by thermoplastic composite 3D printing process, and the overall manufacturing cycle is short, which can meet the rapid manufacturing needs of composite molds in the manufacturing process of composite cover parts.

[0042] As an optional implementation, a composite matrix 100 blank is 3D printed using a thermoplastic composite material and then rough-machined to obtain the composite matrix 100, including the following steps: A 100mm composite substrate blank was printed using a thermoplastic composite 3D printing device; After using a CNC machining center or measuring equipment to check that the allowance on the lower die side of the composite substrate 100 blank is uniform, the connecting surface at the bottom of the composite substrate 100 blank is machined flat, and multiple second waist-shaped holes 111 are machined to obtain the composite substrate 100.

[0043] As an optional implementation, after forming the high-temperature resistant gel coat layer 400, the following steps are also included: The surface of the high-temperature resistant gel coat layer 400 was measured using a coordinate measuring machine.

[0044] The surface of the high-temperature resistant gel coat layer 400 is inspected using a coordinate measuring machine to check whether its surface curvature meets the standard, thereby indirectly checking whether the thickness uniformity of the high-temperature resistant gel coat layer 400 meets the qualification standard. The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A 3D printing composite molding die, characterized in that, include: The composite substrate has a top surface that is a molding surface. A base, the base being connected to the bottom of the composite substrate; A Z-direction limiting structure is disposed between the composite substrate and the base, and the Z-direction limiting structure is used to limit the Z-direction displacement of the composite substrate under high temperature conditions; The Z-axis confinement structure includes: Multiple first oblong holes are formed on the base; Multiple second waist-shaped holes are formed at the bottom of the composite substrate, and the positions of the second waist-shaped holes correspond one-to-one with the positions of the first waist-shaped holes; the center positions of the second waist-shaped holes correspond to the center positions of the first waist-shaped holes, and the length directions of the second waist-shaped holes and the first waist-shaped holes are perpendicular to each other; Multiple connectors, each connector passing through the center of the first oblong hole and the corresponding second oblong hole, to connect the base to the bottom of the composite substrate; The base includes: Square steel frame; Multiple reference blocks are connected to the bottom of the square steel frame; A reference plate is connected to the top surface of the square steel frame, and a plurality of the first waist-shaped holes are all opened through the reference plate; The composite matrix includes: The main frame has a top surface that is a shaped surface, and a plurality of second waist-shaped holes are formed at the bottom of the main frame; A supporting lattice is disposed within the main frame; the supporting lattice is a wave-shaped supporting structure.

2. The 3D printing composite molding die as described in claim 1, characterized in that, The main frame is provided with a high-temperature resistant gel coat layer on its molding surface.

3. A manufacturing method, characterized in that, The method for manufacturing a 3D printed composite molding die as described in claim 1 or 2 includes the following steps: A composite matrix blank is 3D printed using thermoplastic composite materials and then rough-machined to obtain the composite matrix. Select the corresponding universal metal base from the standard module library according to the design specifications; The rough-machined composite substrate is combined with the general-purpose metal base using connectors to obtain an assembly; The assembly is subjected to aging heat treatment according to the aging heat treatment parameters of the thermoplastic composite material used, in order to remove the internal stress of the assembly; A molding surface is precision machined on the top surface of the composite substrate of the assembly; wherein the molding surface is a curved surface; Clean the molding surface thoroughly, and then evenly spray a high-temperature resistant gel coat onto the molding surface area to form a high-temperature resistant gel coat layer.

4. The manufacturing method as described in claim 3, characterized in that, The process of 3D printing a composite matrix blank using thermoplastic composite material and then performing rough machining to obtain the composite matrix includes the following steps: A composite matrix blank was printed using a thermoplastic composite 3D printing device; After using a CNC machining center or measuring equipment to check that the allowance on the lower die side of the composite substrate blank is uniform, the connecting surface at the bottom of the composite substrate blank is machined flat, and multiple second waist-shaped holes are machined to obtain the composite substrate.

5. The manufacturing method as described in claim 3, characterized in that, After forming the high-temperature resistant gel coat layer, the following steps are also included: The surface of the high-temperature resistant gel coat layer was measured using a coordinate measuring machine.

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