A composite material liquid forming device with fiber prestress

Abstract

This invention discloses a liquid molding device for composite materials with fiber prestress, comprising a lower mold, a clamping body, and an upper mold from bottom to top. The top surface of the lower mold has an inner cavity through which liquid polymer material flows sequentially from front to back, passing through the inlet channel, the cavity, and the outlet channel. The clamping body is placed above the lower mold cavity and includes a support, a fixed clamping component, a movable clamping component, and a sliding component. The fixed clamping component is connected to the left side of the support, and the movable clamping component is connected to the right side of the support via the sliding component. Fiber cloth is fixed between the two clamping components and bears prestress when the movable clamping component moves to the right. The upper mold has corresponding inlet / outlet ports, positioning holes, and connecting holes. This device can realize liquid molding of composite materials with fiber prestress and allows for online adjustment of the liquid polymer material formulation, making it particularly suitable for liquid molding processes of composite materials under certain pressure.

Description

Technical Field

[0001] This invention relates to a molding apparatus for polymer materials, and more particularly to a liquid molding apparatus for polymer composite materials with fiber prestress. Background Technology

[0002] Liquid molding technology for composite materials has wide applications in the polymer field. For example, new technologies such as high-pressure resin transfer molding (HP-RTM) have reduced the manufacturing cycle of carbon fiber composites to minutes, playing a crucial role in the mass production of carbon fiber composites for BMW. This technology uses high pressure to inject resin into a closed molding device pre-laid with fiber reinforcement. Through liquid resin flow filling, impregnation, curing, and demolding, high-quality carbon fiber composite products are obtained.

[0003] The molding apparatus serves as the carrier for liquid molding of polymer composite materials, directly impacting its molding quality and production efficiency. During the molding process, liquid polymer material flows in from the inlet, passes through the mold cavity of the molding apparatus, and solidifies together with reinforcing materials to obtain a product similar in shape to the cavity. The matrix raw materials for liquid molding can be monomers, slurries that have undergone preliminary polymerization / condensation, solutions of polymers and monomers, etc., with polymerization or condensation reactions typically occurring during solidification. To improve molding efficiency, molding equipment is often equipped with a temperature control system, combining electric heating or a mold temperature controller to control the ambient temperature during composite material molding.

[0004] In the molding process of composite materials, applying prestress to the fibers creates compressive stress in the weaker areas of the composite matrix, significantly reducing the thermal residual stress of the composite product and suppressing deformation and microcrack formation. This has become an effective measure to improve the quality of composite products. However, due to the mismatch in the thermal expansion coefficients of the matrix and reinforcing materials (such as fibers), thermal residual stress forms after the composite material cools and solidifies. This can lead to dimensional deformation and reduced fatigue strength in the composite product, and also easily cause microcracks within the composite material, resulting in fiber breakage, delamination, and other damage, thus limiting the improvement of the composite material's lifespan. The prestressed molding mode of composite materials has been successfully applied in the field of concrete pouring construction. For example, patent CN206397164U discloses a fiber prestressed reinforcement tensioning system device. By brushing a resin bonding material onto the fiber cloth, and tightening the screw on the tensioning clamp before the resin cures, the fiber cloth is prestressed. When the expected prestress is reached, the fiber cloth is anchored, ensuring that the fiber cloth is completely and densely bonded to the weaker parts of the beam, thereby reinforcing the locally weak points of the bridge. In addition, patent CN206397164U discloses a tensioning device and method for prestressed fiber mesh reinforced concrete (TRC). During the layered pouring of concrete, the fiber mesh is tensioned by loading bolts to apply prestress, thereby significantly improving the bending and torsion of the fiber mesh in the concrete, delaying the appearance and development of cracks in the TRC under tension or compression, and improving the load-bearing capacity of the component.

[0005] The application of fiber prestressing to polymer composite materials is still in its early stages. For example, patent CN217531960U discloses a prestress control device for composite material structures, which is mainly based on prepreg or resin coating / bonding on fiber cloth, and then prestress is applied to the fibers through an external stretching component. The heating base plate is used to accelerate curing, thereby improving the mechanical properties of the composite material and reducing the adverse effects of thermal residual stress on the service life of the composite material.

[0006] Therefore, current research on the application of fiber prestressing in composite material molding mainly has the following characteristics: (1) It is mainly concentrated in the field of concrete construction engineering. By anchoring prestressed fiber cloth or resin-coated fiberboard into the concrete of the building, the deflection deformation, crack formation and development of the concrete structure are reduced, thereby increasing the ultimate load and shear stress of the building structure.

[0007] (2) Existing fiber prestressed molding devices for polymer composites lack a sealing structure and are difficult to be effectively applied to liquid molding processes of composites, especially molding processes with a certain liquid pressure.

[0008] (3) Existing fiber prestressed molding devices for polymer composite materials mainly use prepreg as raw material for molding. Due to the lack of an independent flow channel system, it is impossible to adjust the polymer material formula online, and it is difficult to improve the raw material parameters of composite materials. Summary of the Invention

[0009] The purpose of this invention is to provide a liquid molding apparatus for composite materials with fiber prestress, which has an independent flow channel and a sealing structure, and can impregnate liquid polymer materials on prestressed fiber cloth online, especially suitable for liquid molding processes with a certain pressure.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A liquid forming apparatus for composite materials with fiber prestressing, comprising, from bottom to top, a lower mold, a clamping body, and an upper mold, wherein: The top surface of the lower mold is provided with an inner cavity and a sealing groove from the inside to the outside. The sealing groove is provided with 1 to 4 positioning holes and 1 to 4 connecting holes. The inner cavity is provided with a feed channel, a cavity and a discharge channel from front to back. The clamping body includes a bracket, a fixed clamping component, a movable clamping component, and a sliding component. A long strip-shaped fixed clamping component is fixedly installed on the left side of the bracket; a long strip-shaped movable clamping component is provided on the right side of the bracket. The movable clamping component is connected to the bracket by 1 to 4 sets of sliding components that can slide left and right; the two ends of the fiber cloth are respectively fixed between the fixed clamping component and the movable clamping component, and the fiber cloth bears prestress when the movable clamping component moves to the right; the clamping body is placed on the upper surface of the cavity. The upper mold includes 1 to 8 feed ports, 1 to 8 discharge ports, 1 to 4 connecting holes, 1 to 4 positioning holes, and 1 to 4 cover lifting holes; wherein, the feed ports are connected to the feed channel, the discharge ports are connected to the discharge channel, the positioning holes of the upper mold and the positioning holes of the lower mold are connected through positioning components, and the connecting holes of the upper mold and the connecting holes of the lower mold are connected through fasteners.

[0011] Furthermore, the fixed clamping component is formed by fastening an upper fixed clamping member and a lower fixed clamping member together; the movable clamping component is formed by fastening an upper movable clamping member and a lower movable clamping member together.

[0012] Furthermore, the upper surface of the lower fixed clamping member is provided with a cavity with a depth of 3-15mm; the upper surface of the lower movable clamping member is provided with a cavity with a depth of 3-15mm.

[0013] Furthermore, the longitudinal cross-section of the feed channel gradually increases from front to back; the bottom surface of the feed channel is 1-6mm higher than the bottom surface of the cavity, and the bottom surface of the discharge channel is 0.5-5mm higher than the bottom surface of the cavity.

[0014] Furthermore, an end face groove is formed on the inner surface of the left side of the bracket, and a structure that matches the end face groove is machined on the fixed clamping component for connection; a threaded hole that runs through the left and right sides is formed on the movable clamping component, and the prestressed bolt acts on the right surface of the bracket through the threaded hole.

[0015] Furthermore, a slot for sensors is provided near the prestressed bolts on the bracket.

[0016] Furthermore, a manual gap adjustment assembly is provided on the top surface of the upper mold. The manual gap adjustment assembly includes a connecting rod that runs vertically through the upper mold; a shoulder is provided at the upper end of the connecting rod, and a pad is locked onto the shoulder of the connecting rod by a nut; a pressure plate is connected to the lower end of the connecting rod by a thread; and a limiting block is placed between the pad and the upper mold to adjust the gap between the lower surface of the pressure plate and the lower mold cavity.

[0017] Furthermore, an electro-hydraulic controlled automatic gap adjustment component is provided on the top surface of the upper mold. The automatic gap adjustment component is vertically inserted through the upper mold, and its lower end is connected to the pressure plate by a thread.

[0018] The beneficial effects of this invention are: (1) It can realize the online impregnation of liquid polymer materials on prestressed fiber cloth to prepare high-performance composite materials. By setting a liquid polymer flow channel system in the lower mold and setting a structure on the clamping body to apply and regulate the prestress of the fiber cloth, the requirements of polymer liquid molding and fiber prestress application are met at the same time; (2) It has an independent sealing structure, which can ensure the effective implementation of the liquid molding process of polymer materials, and is especially suitable for liquid molding processes with a certain pressure; (3) It is equipped with an independent flow channel system, which can adjust the formulation of liquid polymer materials online and improve the raw material parameters of composite materials to prepare high-quality composite materials that meet the requirements of different application scenarios. Attached Figure Description

[0019] Figure 1 This is an exploded view of the structure of the device of the present invention; Figure 2 This is a diagram showing the positional relationship between the clamping body and the lower mold of the device of the present invention; Figure 3 This is a schematic diagram of the liquid forming principle of the composite material with fiber prestressing of the present invention; Figure 4 This invention is a prestressed clamping method without pre-curing of fiber cloth; Figure 5 This invention relates to a prestressed clamping method with pre-cured fiber cloth. Figure 6 This is the detection principle of the fiber prestress value of the present invention; Figure 7This is a manual gap adjustment device for the composite material molding area of ​​the device of the present invention; Figure 8 This invention relates to an automatic gap adjustment device for the composite material molding area. Implementation

[0020] The specific implementation schemes of the present invention will now be described with reference to the accompanying drawings and embodiments.

[0021] Figures 1-2 The illustration schematically depicts a composite material liquid molding device with fiber prestressing according to an embodiment of the present invention, comprising, from bottom to top, a lower mold 1, a clamping body 2, and an upper mold 3. Specifically, the top surface of the lower mold 1 has, from the inside out, an inner cavity 11 and a sealing groove 12. The sealing groove 12 has 1-4 positioning holes 13 and 1-4 connecting holes 14 arranged around its periphery. The inner cavity 11 has, from front to back, a feed channel 111, a cavity 112, and a discharge channel 113.

[0022] The clamping body 2 includes a bracket 21, a fixed clamping component 22, a movable clamping component 23, and a sliding component 24. A long strip-shaped fixed clamping component 22 is fixedly installed on the left side of the bracket 21, and a long strip-shaped movable clamping component 23 is provided on the right side of the bracket 21. The movable clamping component 23 is connected to the bracket 21 by 1 to 4 sets of sliding components 24 that can slide left and right. The two ends of the fiber cloth 25 are respectively fixed between the fixed clamping component 22 and the movable clamping component 23. The fiber cloth 25 bears prestress when the movable clamping component 23 moves to the right. The clamping body 2 is placed on the upper surface of the cavity 112.

[0023] The upper mold 3 includes 1 to 8 feed ports 31, 1 to 8 discharge ports 32, 1 to 4 connecting holes 33, 1 to 4 positioning holes 34, and 1 to 4 lifting holes 35. Among them, the feed ports 31 are connected to the feed channel 111, the discharge ports 32 are connected to the discharge channel 113, the positioning holes 34 of the upper mold 3 are connected to the positioning holes 13 of the lower mold 1 through positioning parts, and the connecting holes 33 of the upper mold 3 are connected to the connecting holes 14 of the lower mold 1 through fasteners. Connecting lugs can be installed on the lifting holes 35 for mold opening.

[0024] Since different polymer composite materials have different curing temperatures, heating holes 36 and 15 can be set in the upper mold 3 and lower mold 1, respectively, to introduce liquid of a certain temperature or to use electric heating, etc., to regulate the temperature of the polymer composite material in the cavity 112, thus further expanding the application field of this patent.

[0025] Figure 3The schematic diagram illustrates the principle of liquid molding of the composite material with fiber prestress according to the present invention. During the molding process, the liquid polymer material flows sequentially along the flow direction 2A through the feed channel 111 and the cavity 112, and finally flows out from the discharge channel 113. The longitudinal cross-section of the feed channel 111 gradually increases from front to back. The bottom surface of the feed channel 111 is 1-6 mm higher than the bottom surface of the cavity 112, and the bottom surface of the discharge channel 113 is 0.5-5 mm higher than the bottom surface of the cavity 112. The clamping body 2 is placed on the upper surface of the cavity 112, with its left end fixed to the fixed clamping component 22 and its right end fixed to the movable clamping component 23. The movable clamping component 23 stretches the fiber cloth along the prestress direction 2B to apply prestress.

[0026] Figures 4-5 The illustration schematically depicts the clamping method of the composite material liquid molding device with fiber prestressing of the present invention. The fixed clamping component 22 is formed by a fastening connection between an upper fixed clamping member 221 and a lower fixed clamping member 222 (connected and fixed by fasteners 26); the movable clamping component 23 is formed by a fastening connection between an upper movable clamping member 231 and a lower movable clamping member 232. In specific implementations, such as... Figure 4 As shown, the fiber cloth 25 is wound around the outer surfaces of the lower fixed clamp 222 and the lower movable clamp 232 at both ends; a textured structure is provided on the contact surfaces of the upper fixed clamp 221 and the lower fixed clamp 222, and on the contact surfaces of the upper movable clamp 231 and the lower movable clamp 232, to increase the frictional resistance during the clamping process of the fiber cloth. Figure 5 As shown, to enhance the clamping effect, resin can be added to both ends of the fiber cloth 25 for pre-curing treatment to form pre-cured ends 27 with a certain strength. At the same time, pre-cured cavities 28 with a depth of 3-15mm are opened on the upper surface of the lower fixed clamping member 222 and the upper surface of the lower movable clamping member 232, respectively, and the pre-cured ends 27 are placed in them, thereby further enhancing the reliability of fiber cloth clamping during the application of prestress.

[0027] Figure 6This diagram illustrates the principle of detecting fiber prestress values ​​in a liquid molding apparatus for composite materials with fiber prestress. An end face groove is formed on the inner left side of the support 21. A structure that mates with the end face groove is machined on the fixed clamping component 22 for connection. A threaded hole 233 is formed on the movable clamping component 23, and the prestressing bolt 4 acts on the right surface of the support through the threaded hole 233. A torque wrench can be used to rotate the prestressing bolt 4, and the applied torque is converted into a preload force that pushes the movable clamping component 23 outward, giving the fiber cloth 25 a certain tensile stress. The magnitude of the bolt preload force is the magnitude of the prestress, which can be calculated from the value on the torque wrench. In a specific implementation, a sensor groove 211 can be formed on the support 21 near the threaded hole 233; the prestressing bolt 4 rests on the sensor 5, and rotating the prestressing bolt 4 pushes the movable clamping component 23 to the right, giving the fiber cloth 25 a certain tensile stress. Simultaneously, the prestress value can be observed in real time on the display 6, thus providing a more intuitive understanding of the prestress value.

[0028] Figure 7 This diagram schematically illustrates the manual gap adjustment device for the composite material molding area of ​​a fiber-prestressed composite material liquid molding apparatus according to the present invention. A manual gap adjustment assembly 7 is provided on the top surface of the upper mold 3, including a connecting rod 71 vertically penetrating the upper mold 3; a shoulder is provided at the upper end of the connecting rod 71, and a pad 73 is locked onto the shoulder of the connecting rod by a nut 72; a pressure plate 74 is threadedly connected to the lower end of the connecting rod 71, allowing the gap adjustment assembly to move freely up and down; a limiting block 75 is placed between the pad 73 and the upper mold 3 to adjust the gap between the lower surface of the pressure plate 74 and the lower mold cavity 112; a limiting block of appropriate thickness is selected according to the gap thickness requirements of different processes. By setting up a gap adjustment device, the application scope of this patent is further expanded.

[0029] Figure 8 The illustration schematically depicts the automatic gap adjustment device in the composite material molding area of ​​a fiber-prestressed composite material liquid molding apparatus according to the present invention. An electro-hydraulic controlled automatic gap adjustment component 8 is provided on the top surface of the upper mold 3, vertically penetrating the upper mold 3, and its lower end is connected to the pressure plate 74 via a thread. The automatic gap adjustment component 8 can be driven up and down by electrical or hydraulic means to automatically adjust the gap between the lower surface of the pressure plate 74 and the lower mold cavity 112.

[0030] In specific implementation, the composite material with fiber prestress is prepared according to the following steps: The first step is to assemble the prestressed fiber clamping body. Wrap the two ends of the fiber cloth 25 around the fixed clamping member 22 and the movable clamping member 23 respectively. Fix the fixed clamping member 22 to the left side of the bracket 21. Connect the movable clamping member 23 to the right side of the bracket 21 using the sliding member 24. Adjust the prestressing bolt 4 to apply force to the right side of the bracket, allowing the movable clamping member 23 to move to the right on the sliding member 24 to stretch the fiber cloth 25. The distance between the two clamping members gradually increases, thereby applying prestress to the fiber cloth 25. After assembling the prestressed fiber clamping body 2, place it in the cavity 112 of the lower mold.

[0031] The second step is the mold assembly of the liquid molding device. Place the sealing ring in the sealing groove 12; connect the positioning hole 34 of the upper mold 3 with the positioning hole 13 of the lower mold 1 through the positioning component; then connect the connecting hole 33 of the upper mold 3 with the connecting hole 14 of the lower mold 1 through the fastener.

[0032] The third step is to inject liquid polymer material from the feed port 31 of the upper mold 3, and enter the cavity 112 through the feed channel 111. After filling the cavity 112, the excess material overflows to the discharge channel 113 and is then discharged through the discharge port 32, waiting for the composite material in the cavity 112 to complete the curing and molding.

[0033] Fourth step: After the composite material has cured, remove the fasteners and positioning parts of the upper mold 3 and the lower mold 1; separate the upper mold 3 and the lower mold 1, and take out the clamping body 2; adjust the prestressing bolt 4 to release the prestress acting on the fiber cloth 25, cut and peel off the fiber cloth 25 wrapped on the fixed clamping part 22 and the movable clamping part 23, and remove the sliding part 24, the fixed clamping part 22 and the movable clamping part 23 to obtain the prestressed fiber composite material product.

Claims

1. A liquid forming device for composite materials with fiber prestress, comprising, from bottom to top, a lower mold (1), a clamping body (2), and an upper mold (3), characterized in that: The top surface of the lower mold (1) is provided with an inner cavity (11) and a sealing groove (12) from the inside to the outside. The sealing groove (12) is provided with 1 to 4 positioning holes (13) and 1 to 4 connecting holes (14) around its periphery. The inner cavity (11) is provided with a feed channel (111), a cavity (112) and a discharge channel (113) from front to back. The bottom surface of the feed channel (111) is higher than the bottom surface of the cavity (112), and the bottom surface of the discharge channel (113) is higher than the bottom surface of the cavity (112). The clamping body (2) includes a bracket (21), a fixed clamping component (22), a movable clamping component (23), and a sliding component (24). A long strip-shaped fixed clamping component (22) is fixedly installed on the left side of the bracket (21). A long strip-shaped movable clamping component (23) is provided on the right side of the bracket (21). The movable clamping component (23) is connected to the bracket (21) by 1 to 4 sets of sliding components (24) that can slide left and right. The two ends of the fiber cloth (25) are respectively fixed between the fixed clamping component (22) and the movable clamping component (23). The fiber cloth (25) bears prestress when the movable clamping component (23) moves to the right. The clamping body (2) is placed as a whole in the molding space enclosed by the sealing groove (12). The clamping body (2) is placed on the upper surface of the cavity (112). The upper mold (3) includes 1 to 8 feed ports (31), 1 to 8 discharge ports (32), 1 to 4 connecting holes (33), 1 to 4 positioning holes (34), and 1 to 4 cover opening holes (35); wherein, the feed port (31) is connected to the feed channel (111), the discharge port (32) is connected to the discharge channel (113), the positioning hole (34) of the upper mold (3) is connected to the positioning hole (13) of the lower mold (1) and connected by positioning components, and the connecting hole (33) of the upper mold (3) is connected to the connecting hole (14) of the lower mold (1) and connected by fasteners.

2. The composite material liquid forming device with fiber prestress according to claim 1, characterized in that: The longitudinal cross section of the feed channel (111) gradually increases from front to back; the bottom surface of the feed channel (111) is 1-6 mm higher than the bottom surface of the cavity (112), and the bottom surface of the discharge channel (113) is 0.5-5 mm higher than the bottom surface of the cavity (112).

3. The composite material liquid forming device with fiber prestress according to claim 1, characterized in that: The fixed clamping component (22) is formed by fastening the upper fixed clamping component (221) and the lower fixed clamping component (222); the movable clamping component (23) is formed by fastening the upper movable clamping component (231) and the lower movable clamping component (232).

4. The composite material liquid forming device with fiber prestress according to claim 3, characterized in that: The upper surface of the lower fixed clamping member (222) is provided with a cavity with a depth of 3-15mm; the upper surface of the lower movable clamping member (232) is provided with a cavity with a depth of 3-15mm.

5. The composite material liquid forming device with fiber prestress according to claim 1, characterized in that: The bracket (21) has an end face groove on its left inner surface. The fixed clamping component (22) has a structure that matches the end face groove and is connected to it. The movable clamping component (23) has a threaded hole (233) that runs through the left and right sides. The prestressed bolt (4) acts on the right surface of the bracket through the threaded hole (233).

6. The composite material liquid forming apparatus with fiber prestress according to claim 5, characterized in that: A sensor slot (211) is provided near the point where the prestressed bolt (4) is applied.

7. The composite material liquid forming device with fiber prestress according to claim 1, characterized in that: The top surface of the upper mold (3) is provided with a manual gap adjustment component (7), which includes a connecting rod (71) that runs vertically through the upper mold (3); a shoulder is provided at the upper end of the connecting rod (71), and a pad (73) is locked on the shoulder of the connecting rod by a nut (72); a pressure plate (74) is connected to the lower end of the connecting rod (71) by a thread; a limiting block (75) is placed between the pad (73) and the upper mold (3) for adjusting the gap between the lower surface of the pressure plate (74) and the lower mold cavity (112).

8. The composite material liquid forming device with fiber prestress according to claim 1, characterized in that: An electro-hydraulic controlled automatic gap adjustment component (8) is provided on the top surface of the upper mold (3). The automatic gap adjustment component (8) is vertically inserted through the upper mold (3), and its lower end is connected to the pressure plate (74) by a thread.

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