A combined mold for reducing winding residual stress of a composite cylindrical shell

Abstract

The present application belongs to the technical field of composite material processing, and particularly relates to a combined mold for reducing residual stress of a composite material cylindrical barrel winding, which comprises a rectangular mandrel main body section, a clamping section and a stress relief section. Four planes of the rectangular mandrel main body section are provided with grooves, and the groove edges are provided with scale supporting clamping grooves. The clamping section is integrally connected with the rectangular mandrel main body section. The stress relief section is provided with a telescopic chuck device, and the stress relief section is embedded in the groove of the rectangular mandrel main body. The present application can unload the residual stress generated by the winding fiber by the up and down movement of the mold stress relief section, effectively solves and improves the problem that the composite material cylindrical barrel is deformed due to the residual stress generated after the winding tension is applied during the winding process, and compared with the residual stress elimination method by vibration aging, the mold is simple to operate and does not consume energy.

Description

Technical Field

[0001] This invention belongs to the field of composite material processing technology, and specifically relates to a combined mold for reducing the residual stress of composite material cylindrical winding. Background Technology

[0002] Fiber winding is a composite material molding process characterized by high molding efficiency, high fiber strength utilization, and good process controllability. It is widely used in military and civilian industries, such as for missile casings, cylindrical / cylindrical launch tubes, engine casings, radomes, pressure vessels, pipes, and flywheels. Based on the different states of fiber impregnation with resin during the winding process, it is divided into three types: wet winding, dry winding, and semi-dry winding, with wet and dry winding being the most commonly used. Compared to wet winding, dry winding offers advantages such as more stable product quality, faster winding speed, environmental friendliness, and precise control of resin content, and is receiving increasing attention and use in the field of composite material winding.

[0003] Winding tension is one of the key factors affecting the performance of wound structures. Applying winding tension significantly affects the internal stress distribution of composite wound structures before service, thus affecting the efficiency of the winding layer. During the molding process of composite cylindrical tubes, the application of winding tension during fiber winding will accumulate residual stress between the winding layers. The residual stress generated during the winding process will affect the quality of the composite wound product. If the residual stress is not eliminated or reduced, the composite cylindrical product will have defects such as dents and deformation after curing, which will seriously reduce the performance of the wound cylindrical tube and affect the use of the product.

[0004] Traditional methods for eliminating residual stress in wound composite materials mainly fall into two categories: thermal aging and vibration aging. Thermal aging is not suitable for eliminating residual stress in carbon fiber composites. Vibration aging, on the other hand, involves cyclically loading the workpiece under vibration to induce resonance, generating alternating stress. This alternating stress then combines with the existing residual stress within the workpiece, causing yielding in localized areas of peak stress. This results in minute plastic deformation, altering the original stress field and thus homogenizing the internal stress distribution, ultimately releasing the residual stress. However, vibration aging is a complex and energy-intensive process.

[0005] For example, patent number CN108774667 B discloses a device and method for synergistically eliminating stress using thermal aging and vibration aging. This device includes a vibration system, a heating system, and a cooling system. The cooling system cools the vibration table in the vibration system, and the exciter and sensor are fixed to the cooling end of the vibration table. A workpiece fixing device fixes the workpiece on the vibration table and extends it into the furnace cavity of the high-temperature furnace in the heating system, thus achieving synergistic stress elimination through thermal aging and vibration aging. This method of synergistic stress elimination utilizes the effective elimination of residual stress by both thermal aging and vibration aging, and its synergistic effect significantly improves the stress elimination effect of single thermal aging or vibration aging and combined treatments. It is applicable to stress elimination in ferrous metals, polymers, non-ferrous metals, composite materials, etc. However, the stress elimination method provided by this invention, which includes thermal aging and vibration aging, is relatively cumbersome and requires numerous equipment and tools, which is not conducive to energy conservation and emission reduction.

[0006] Therefore, how to solve the problem of reducing or eliminating residual stress in composite cylindrical products, and improve efficiency and reduce energy consumption, is an urgent topic that needs to be addressed and studied.

[0007] This invention designs a combined mold for reducing residual stress during the winding of composite cylindrical products. This directly reduces residual stress during the winding process of composite cylindrical products, solving problems such as product deformation and dents. The process is simple and easy to operate. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a combined mold for reducing the residual stress of composite cylindrical winding.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0010] A combined mold for reducing residual stress during the winding of composite cylindrical tubes is disclosed. The combined mold includes a rectangular mandrel body section, a clamping section, and a stress relief section. The rectangular mandrel body section has grooves on its four planes. The clamping section is integrally connected to the rectangular mandrel body section. The stress relief section is embedded in the groove of the rectangular mandrel body. The inner wall of the groove has a support slot. The end of the stress relief section has a chuck device. The installation height of the stress relief section in the groove can be adjusted by the chuck device and the support slot.

[0011] The rectangular mandrel body consists of a main body segment, grooves, and support slots. The main body segment has grooves on its four planes, and each groove has a graduated support slot on its two edges.

[0012] The groove is located on the central axis of the mandrel body plane. The width of the groove is 5-10 mm, the depth of the groove is 20-40 mm, and the length of the groove is the same as the length of the mandrel body section.

[0013] The overall width of the support slot is 20-40mm. The support slot has a serrated structure with 3-6 serrations. The scale spacing of the serrations in each support slot is 1-3mm, and the height of the serrations is 5-12mm.

[0014] The stress relief section consists of a base section and a chuck device. The base section consists of a wall panel and screws, with the screws welded to the wall panel. The chuck device is a telescopic chuck, which is a hinge structure consisting of a hinge, a threaded hole, and a hinge plate. When the two hinge plates of the chuck are opened, they can be locked onto the support slot.

[0015] The base section has a convex structure with an overall width of 4.5–9.5 mm and a height of 20–40 mm. The length of the upper half of the base section is the same as the length of the groove in the main body section of the mandrel. The length of the protruding part of the lower half of the base section is 0.85–0.95 of the length of the upper half.

[0016] The height of the chuck device is 4 to 10.5 mm. When the chuck device is built into the serrations of the support slot, the upper half of the base section is higher than the plane of the rectangular mandrel main body section. When the chuck device is moved down to the bottom of the support slot, the upper half of the base section is flush with the plane of the rectangular main body section.

[0017] The chuck device of the stress relief section is connected to the lower half of the base section by bolts.

[0018] The combined mold is made of Q235 steel.

[0019] The clamping section and the rectangular mandrel body are welded together.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. By moving the mold stress relief section up and down, the residual stress generated by the winding fiber is relieved, which can effectively solve and improve the problem of deformation of the composite cylindrical tube caused by residual stress after the winding tension is applied during the winding process of composite cylindrical tube.

[0022] 2. The height of the stress relief section can be finely adjusted according to the magnitude of the residual stress to offset the residual stress. At the same time, after the stress relief section is lowered, the winding fiber layer is reset, which does not affect the flatness of the inner surface of the composite cylindrical product.

[0023] 3. The modular and detachable mold design improves the efficiency and quality of demolding composite material products by pre-disassembling the stress relief section;

[0024] 4. Compared with the method of eliminating residual stress by vibration aging, this method is simple and energy-free;

[0025] 5. The mold is easy to use and operate.

[0026] Based on the above description, the combined mold of the present invention for reducing the residual stress of composite cylindrical winding can be used as a solution to reduce or eliminate the deformation of composite cylindrical products. Attached Figure Description

[0027] Figure 1 This is a general structural diagram of a combined mold for reducing residual stress when winding composite cylindrical tubes according to the present invention.

[0028] Figure 2 This is a diagram showing the opening and closing effects of the stress relief section.

[0029] Figure 3 This is a structural diagram of the base segment.

[0030] Figure 4 This is a diagram showing the opening and closing of the chuck device.

[0031] In the attached diagram: 100 is the main body section of the mandrel, 200 is the stress relief section, and 300 is the clamping section;

[0032] 101 is the main section of the mandrel body, 102 is the groove of the mandrel body, and 103 is the support slot of the mandrel body.

[0033] 201 is the base section of the stress relief section, and 202 is the chuck device of the stress relief section;

[0034] 2011 is the wall panel of the base section, and 2012 is the screw on the base section;

[0035] 2021 is the threaded hole of the chuck device, 2022 is the hinge plate of the chuck device, and 2023 is the hinge. Detailed Implementation

[0036] This invention discloses a combined mold for reducing residual stress during the winding of composite cylindrical tubes. The combined mold includes a rectangular mandrel main body, a clamping section, and a stress relief section. The rectangular mandrel main body has grooves on its four planes. The clamping section is integrally connected to the rectangular mandrel main body. The stress relief section is embedded in the groove of the rectangular mandrel main body. The inner wall of the groove has a support slot. The end of the stress relief section has a chuck device. The installation height of the stress relief section in the groove can be adjusted by the chuck device and the support slot.

[0037] The rectangular mandrel body consists of a main body segment, grooves, and support slots. The main body segment has grooves on its four planes, and each groove has a graduated support slot on its two edges.

[0038] The groove is located on the central axis of the mandrel body plane. The width of the groove is 5-10 mm, the depth of the groove is 20-40 mm, and the length of the groove is the same as the length of the mandrel body section.

[0039] The overall width of the support slot is 20-40mm. The support slot has a serrated structure with 3-6 serrations. The scale spacing of the serrations in each support slot is 1-3mm, and the height of the serrations is 5-12mm.

[0040] The stress relief section consists of a base section and a chuck device. The base section consists of a wall panel and screws, with the screws welded to the wall panel. The chuck device is a telescopic chuck, which is a hinge structure consisting of a hinge, a threaded hole, and a hinge plate. When the two hinge plates of the chuck are opened, they can be locked onto the support slot.

[0041] The base section has a convex structure with an overall width of 4.5–9.5 mm and a height of 20–40 mm. The length of the upper half of the base section is the same as the length of the groove in the main body section of the mandrel. The length of the protruding part of the lower half of the base section is 0.85–0.95 of the length of the upper half.

[0042] The height of the chuck device is 4 to 10.5 mm. When the chuck device is built into the serrations of the support slot, the upper half of the base section is higher than the plane of the rectangular mandrel main body section. When the chuck device is moved down to the bottom of the support slot, the upper half of the base section is flush with the plane of the rectangular main body section.

[0043] The chuck device of the stress relief section is connected to the lower half of the base section by bolts.

[0044] The combined mold is made of Q235 steel.

[0045] The clamping section and the rectangular mandrel body are welded together.

[0046] Before winding the fiber or prepreg, adjust the chuck device so that it is built into the support slot, making the stress relief section of the combined mold slightly higher than the plane of the main body of the rectangular mandrel, thus tightening the wound fiber. After winding, adjust the chuck device so that the stress relief section moves down to the bottom of the support slot, and finally the upper surface of the stress relief section is parallel to the plane of the main body of the rectangular mandrel, thus relieving the stress on the fiber winding layer. At the same time, the wound fiber layer is reset and fits into the mold, thereby reducing and eliminating the residual stress during the winding process, without affecting the flatness of the inner surface of the composite cylindrical product.

[0047] During the demolding process of composite cylindrical products, the stress relief section is first extracted before the product is demolded.

Claims

1. A combined mold for reducing winding residual stress of a composite material cylindrical shell, characterized by, The combination mold comprises a rectangular mandrel main body section, a clamping section and a stress relief section, four planes of the rectangular mandrel main body section are provided with grooves, the clamping section is integrally connected with the rectangular mandrel main body section, the stress relief section is embedded in the grooves of the rectangular mandrel main body, the inner wall surface of the grooves is provided with a supporting clamping groove, the end of the stress relief section is provided with a chuck device, and the installation height of the stress relief section in the grooves is adjusted through the chuck device and the supporting clamping groove. The overall width of the supporting clamping groove is 20-40 mm, the supporting clamping groove is in a sawtooth structure, the number of the sawteeth is 3-6, the scale interval of the sawteeth of each supporting clamping groove is 1-3 mm, and the height of the sawteeth is 5-12 mm. The stress relief section is composed of a base section and a chuck device, the base section is composed of a wall plate and a screw, the screw is welded on the wall plate, the chuck device is a telescopic chuck, the telescopic chuck is in a hinge structure and is composed of a hinge, a threaded hole and a hinge plate, and the two hinge plates of the chuck can be clamped on the supporting clamping groove when being opened.

2. The combined mold for reducing winding residual stress of a composite material cylindrical shell according to claim 1, wherein The rectangular mandrel main body is composed of a main body section, grooves and supporting clamping grooves, the four planes of the main body section are provided with grooves, and the two edges of each groove are provided with supporting clamping grooves with scales.

3. The combined mold for reducing winding residual stress of a composite cylindrical shell according to claim 2, wherein The grooves are arranged at the central axis positions of the planes of the mandrel main body, the width of the grooves is 5-10 mm, the depth of the grooves is 20-40 mm, and the length of the grooves is consistent with the length of the mandrel main body section.

4. The combined mold for reducing winding residual stress of a composite material cylindrical shell according to claim 1, wherein The base section is in a convex structure, the overall width is 4.5-9.5 mm, the height is 20-40 mm, the length of the upper half of the base section is consistent with the length of the groove of the mandrel main body section, and the length of the convex part of the lower half of the base section accounts for 0.85-0.95 of the length of the upper half.

5. The combined die for reducing winding residual stress of a composite material cylindrical shell according to claim 1, wherein The height of the chuck device is 4-10.5 mm, when the chuck device is arranged on the sawteeth of the supporting clamping groove, the upper half of the base section is higher than the plane of the rectangular mandrel main body section, and when the chuck device is arranged at the bottom of the supporting clamping groove, the upper half of the base section is flush with the plane of the rectangular main body section.

6. The combined die for reducing winding residual stress of a composite material cylindrical shell according to claim 1, wherein The chuck device of the stress relief section is connected with the lower half of the base section through a bolt.

7. The combined die for reducing winding residual stress of a composite material cylindrical shell according to claim 1, wherein The material of the combination mold is Q235 steel.

8. The combined die for reducing winding residual stress of a composite cylindrical shell according to claim 1, wherein The clamping section and the rectangular mandrel main body are in a welded connection structure.

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