Pressing and embedding type threaded connection structure for composite material plate and assembling method

Abstract

The invention provides a pressing and embedding type threaded connection structure for a composite material plate and an assembling method. The pressing and embedding type threaded connection structure comprises a metal clamping plate, the composite material plate, a fastening connecting piece and an anti-overpressure limiting block. Dense metal threads are arranged on the contact interface of the metal clamping plate and the composite material plate, the composite material plate is not provided with composite material threads in advance before assembly, and during assembly, the metal threads of the metal clamping plate are pressed and embedded into the composite material rectangular plate through mechanical ballast equipment to form an occlusion interface of the composite material threads and the dense threads; and mechanical interlocking and firm combination between the metal clamping plate and the composite material rectangular plate are achieved through the fastening connecting piece and the applied fastening force, and the integrated design of the forming process and the structure construction is achieved. According to the method, secondary machining does not need to be conducted on the composite material rectangular plate, base material section weakening and initial defects caused by mechanical hole forming and tooth groove pre-forming can be avoided, the heterogeneous material interface performance and the joint bearing capacity can be improved, the assembly process is simple, quality is controllable, reliability is high, and durability is good.

Description

Technical Field

[0001] This invention belongs to the field of high-end equipment manufacturing and high-performance fiber-reinforced composite material connection technology, specifically relating to a press-fit threaded connection structure and assembly method for composite material plates. Background Technology

[0002] High-end equipment in aviation, marine engineering, transportation, and emergency facilities have significant design requirements for lightweight structures. High-performance fiber-reinforced composite materials and products, characterized by their lightweight, high strength, and corrosion resistance, have broad application prospects in the high-end equipment manufacturing industry. Large load-bearing structures or irregularly shaped structures are often assembled from composite material sheets and profiles, requiring efficient connection methods to form robust and reliable connection nodes between intersecting composite material components and between composite materials and metal components. However, fiber-reinforced composite materials cannot be directly welded using methods similar to those used with metals. How to achieve effective connections between composite material sheets and metal components has become a key bottleneck restricting the research and development and large-scale application of high-end equipment.

[0003] For fiber-reinforced composite panels, adhesive bonding and bolting are two of the most common and widely used connection methods. Adhesive bonding, which bonds the material surfaces using adhesives, offers advantages such as avoiding stress concentration caused by drilling and not cutting the fibers. However, its connection strength is significantly affected by environmental factors, resulting in lower strength, a longer curing time, and non-removable nature. It is generally used in lightweight structural components and non-load-bearing structures. In contrast, bolting is widely used in load-bearing structures due to its simple structure, removability, and high reliability. However, its main drawback is that the drilling process during the secondary processing of the composite panel disrupts fiber continuity, leading to significant stress concentration at the hole edges, thus reducing connection strength and efficiency.

[0004] Therefore, there is an urgent need for a composite material plate connection structure that does not require secondary processing of the composite material plate, can fully utilize the interlaminar shear strength of the composite material, and significantly improves the connection efficiency and reliability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a press-fit threaded connection structure and assembly method for composite material plates. The composite material plate is pre-positioned using fastening lugs and elongated lugs of the first and second clamping plates, and an overpressure limiting block is set. Then, the first clamping plate is press-fitted using a mechanical ballast device, thereby pressing the metal threads into the composite material plate to form composite threads and a thread engagement interface composed of composite threads and metal threads. Finally, the first clamping plate, the second clamping plate, and the composite material plate are fixedly connected using fastening connectors, and pre-stress is applied to the thread engagement interface. This eliminates the need for secondary processing of the composite material plate, fully utilizes the interlaminar shear strength of the composite material, and significantly improves connection efficiency and reliability.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution: This invention provides a press-fit threaded connection structure for composite material plates, comprising a composite material plate, and further comprising: A metal clamp for connecting the ends of a composite material plate in the longitudinal direction, the metal clamp including a first clamp and a second clamp for clamping the composite material plate from the upper and lower sides. Both the first clamping plate and the second clamping plate include: The long oval ear plate and the threaded transition plate connected to the inner side of the long oval ear plate are provided. The long oval ear plate has a connecting pin hole. The threaded transition plate is pre-machined with multiple rows of metal threads. The spacing between the multiple rows of metal threads is less than a preset value. Fastening ear plates are provided on both sides of the metal thread area of ​​the threaded transition plate. Both the elongated ear plates and the fastening ear plates are higher than the thickness of the metal thread area plate. When the composite material plate is placed between the first clamping plate and the second clamping plate, the elongated ear plates and the fastening ear plates on both sides are used to abut against the ends of the composite material plate to achieve longitudinal and lateral limiting of the composite material plate. In this limiting state, the longitudinal axis of the composite material plate and the metal clamping plate coincides, and the extension direction of each row of metal threads intersects with the longitudinal axis. Fastening screw holes are provided on the fastening ear plates on both sides and arranged longitudinally at intervals; the fastening screw holes are used to press down the first clamping plate to press the upper and lower sides of the composite material plate to form the composite material thread and the thread engagement interface between the composite material thread and the metal thread, and then screw in the fastening connector to fix the composite material plate and the metal clamping plate. Then, the fastening connector is tightened according to the preset fastening force to generate pre-compression stress at the thread engagement interface to complete the assembly connection of the composite material plate.

[0007] Optionally, it also includes: Before the first clamping plate is pressed down, an overpressure limiting block needs to be placed on the fastening ear plates on both sides of the second clamping plate. The thickness of the overpressure limiting block is greater than the height of the metal thread.

[0008] Optionally, the thickness of the overpressure protection limit block is twice the height of the metal thread.

[0009] Optionally, the metal thread is a fine thread with a tooth angle of 30° to 60°, and the metal thread includes a triangular thread or a sawtooth thread.

[0010] Optionally, the metal thread includes a parallel transverse thread or a parallel herringbone thread.

[0011] Optionally, the inner end of the threaded transition plate away from the elongated lug plate is provided with a gentle chamfer.

[0012] Optionally, the spacing between multiple rows of metal threads is less than 3.0 mm.

[0013] Optionally, the height of the metal thread is 0.5 mm to 1.5 mm.

[0014] Optionally, the composite material plate is a rectangular plate; the composite material plate is hollow or solid. If the composite material plate is hollow, a metal liner needs to be installed in the inner cavity of the composite material plate.

[0015] Secondly, the present invention provides an assembly method for a press-fit threaded connection structure for a composite material plate, which is applied to the press-fit threaded connection structure, the assembly method comprising: Pre-positioning of composite material plate: The second clamping plate with pre-machined metal threads is placed on the lower plate of the mechanical ballast equipment. The end of the composite material plate without composite material threads is placed on the second clamping plate and the first clamping plate is fastened to the composite material plate. The side of the composite material plate is against the fastening lugs of the first and second clamping plates to achieve lateral positioning. The end is against and aligned with the elongated lugs of the first and second clamping plates to achieve longitudinal positioning. In this positioning state, the longitudinal axes of the composite material plate and the metal clamping plate coincide, and the extension direction of each row of metal threads intersects the longitudinal axis. Overpressure limiting blocks are set: the composite material plate remains in a pre-positioned limiting state, and overpressure limiting blocks are placed above the fastening ear plates on both sides of the second clamping plate to limit the downward stroke, so as to prevent the composite material plate from being crushed and damaged during the composite thread forming process. Generate thread engagement interface: The first clamping plate is pressed down by a mechanical ballast device so that the metal threads on the first and second clamping plates are gradually pressed into the upper and lower sides of the composite material plate. After the metal threads are fully embedded in the outer wall of the composite material plate, the pressure is maintained for a preset time and then unloaded, forming composite material threads and thread engagement interface composed of composite threads and metal threads. Install fastening connectors: After the threaded engagement interface is generated, the first clamping plate, the second clamping plate, and the composite material plate remain in the same position. Remove the overpressure limit block and screw the fastening connectors into the fastening screw holes to fix the composite material plate and the metal clamping plate together. Apply lateral fastening force: According to the design value, tighten the fastening connectors in a preset cross sequence to generate pre-compression stress at the thread engagement interface to complete the assembly connection of the composite material plate and the metal clamp.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention clamps the composite material plate from the top and bottom sides by pre-processing the first and second clamping plates with metal threads, and then forms the composite material thread and the thread engagement interface composed of the metal thread by pressing and embedding method. Then, the first and second clamping plates are fixedly connected by fastening connectors. Subsequently, by tightening the fastening connectors to apply a large prestress to the thread engagement interface, the connection and assembly of the composite material plate can be completed.

[0017] This invention eliminates the need for secondary processing of the composite material sheet, meaning it avoids the pre-cutting of grooves and threaded holes directly on the composite material sheet using special turning tools. Instead, metal threads are cut on a metal clamping plate, which is then pressed into the composite material sheet using conventional mechanical ballast equipment. The components are then integrated using fastening connectors on both sides, thus combining the molding process and structural design into a single unit. This simplifies the assembly process and ensures controllable molding quality. Specifically, the composite thread of this invention is formed by pressing metal threads on a first and second clamping plate, followed by direct connection using fastening connectors. The high degree of matching between the metal threads and the composite threads, with negligible gaps at the thread engagement interface, avoids the groove defects and gap errors caused by pre-cutting composite material grooves. This ensures consistency between the molded product and the structural design, improving product molding quality and performance.

[0018] This invention achieves high connection strength and load-bearing capacity. The composite thread of this invention has a smaller size and a smaller meshing surface for each tooth, significantly reducing the damage to the longitudinal continuous fibers of the composite material plate and the cross-sectional attenuation rate. Furthermore, the composite thread forming process directly avoids transverse crushing damage. Therefore, by applying greater tightening force and interfacial pre-stress to the fasteners on both sides, the interlaminar shear strength of the composite material and the joint strength and connection efficiency are effectively enhanced. The spacing of the multiple rows of metal threads in this invention is all less than a preset value to form a dense array, which can fully utilize the shear force transmission effect of the thread meshing interface, enhancing connection strength and load-bearing efficiency. The large number and clustered nature of the composite threads effectively improve connection reliability. After the composite material press-fit threaded connection structure is assembled, when one end of the joint bears an axial load, the axial concentrated force is first transmitted to the elongated ear plate through the connecting pin hole at the end of the metal clamp, then to the thread transition plate, then to the composite material plate through the thread meshing interface, and finally to the joint at the other end. The thread meshing interface mainly relies on the shear action of the composite thread to transmit axial force, with a clear force transmission path and good effect.

[0019] (2) The composite thread of the present invention is a small-sized triangular thread or sawtooth thread, etc. The root of the composite thread is a gentle angle, which can improve the stress concentration problem caused by the rectangular tooth groove of the composite material, reduce the local peak shear stress of the composite material, and improve the overall strength of the joint.

[0020] (3) The bearing capacity of the joint of the present invention is not limited by the number of tooth grooves of composite material and the control of the failure of the first tooth groove. The number, shape and size of composite thread and the length of thread engagement interface can be flexibly set according to the bearing capacity of the joint and the requirements of lightweighting. It has strong design flexibility.

[0021] (4) The metal clamp and composite material plate of the present invention rely on the mechanical interlocking and shearing action of the different materials of the threaded interlocking interface to transmit force, without any adhesive, avoiding the performance degradation, debonding risk and fatigue problem of the adhesive layer under long-term service due to environmental factors in adhesive bonding, and can ensure the durability under complex environment and long-term load.

[0022] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of a press-fit threaded connection structure for composite material plates provided in Embodiment 1 of the present invention.

[0024] Figure 2 This is an exploded structural diagram of a press-fit threaded connection structure for composite material plates provided in Embodiment 1 of the present invention.

[0025] Figure 3 This is a semi-sectional structural diagram of a press-fit threaded connection structure for composite material plates provided in Embodiment 1 of the present invention.

[0026] Figure 4 This is a partial structural diagram of the thread engagement interface of a press-fit type threaded connection structure for composite material plates provided in Embodiment 1 of the present invention.

[0027] Figure 5 This is a schematic diagram of a single metal clamp plate for a press-fit threaded connection structure for composite material plates, provided in Embodiment 1 of the present invention.

[0028] Figure 6 This is a structural arrangement diagram of the first and second clamping plates of a set of press-fit threaded connection structures for composite material plates provided in Embodiment 1 of the present invention.

[0029] Figure 7 This is a longitudinal cross-sectional view of the effect of the composite thread before forming in a press-fit type threaded connection structure for composite material plates, provided in Embodiment 1 of the present invention.

[0030] Figure 8 This is a longitudinal cross-sectional view of the effect of composite thread forming on a press-fit type threaded connection structure for composite material plates, provided in Embodiment 1 of the present invention.

[0031] Figure 9 This is a three-dimensional schematic diagram of the effect of composite thread forming after the press-fit type threaded connection structure for composite material plates provided in Embodiment 1 of the present invention.

[0032] Figure 10 This is a schematic diagram of the spatial arrangement of an overpressure limiting block for a press-fit type threaded connection structure for composite material plates, provided in Embodiment 1 of the present invention.

[0033] Figure 11 This is a schematic diagram of the overall spatial arrangement of the components before composite thread forming in Embodiment 2 of the present invention.

[0034] Figure 12 This is a partial schematic diagram of the spatial arrangement of various components before composite thread forming in Embodiment 2 of the present invention.

[0035] Figure 13 This is a partial schematic diagram of the spatial arrangement of various components after composite thread forming in Embodiment 2 of the present invention.

[0036] Figure 14 This is a schematic diagram of the installation of the fastening connector after the composite material thread is formed in Embodiment 2 of the present invention.

[0037] Figure 15 This is a cross-sectional schematic diagram of the entire press-fit threaded connection structure after the fastening connector is installed in Embodiment 2 of the present invention.

[0038] Figure 16 This is a schematic diagram showing the arrangement of the metal liner tube inside the hollow rectangular plate of the composite material in Embodiment 3 of the present invention.

[0039] Figure 17 This is a partial schematic diagram of the spatial arrangement of various components before composite thread forming in Embodiment 3 of the present invention.

[0040] Figure 18 This is a longitudinal cross-sectional schematic diagram showing the effect of composite material thread forming before and after in Embodiment 3 of the present invention.

[0041] Figure 19 This is a three-dimensional schematic diagram of the entire press-fit threaded connection structure after the fastening fastener is installed in Embodiment 3 of the present invention.

[0042] In the diagram: 1. Metal clamping plate, 2. Composite material plate, 3. Fastening connector, 4. Threaded engagement interface, 5. Overpressure limiting block, 6. Mechanical ballast equipment, 7. Metal liner, 11. First clamping plate, 12. Second clamping plate, 13. Metal thread, 131. Parallel transverse thread, 132. Parallel oblique thread, 14. Fastening lug, 15. Fastening screw hole, 16. Connecting pin hole, 17. Elongated lug, 18. Threaded transition plate, 19. Gentle chamfer, 21. Composite material thread, 31. Fastening screw, 32. Fastening nut. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances. Example 1

[0046] This embodiment provides a press-fit dense threaded connection structure for composite material plates, such as... Figure 1 , Figure 2 and Figure 3As shown, it includes a metal clamping plate 1, a composite material plate 2, and a fastening connector 3. The metal clamping plate 1 is used to connect to the end of the composite material plate 2 in the longitudinal direction. The metal clamping plate 1 includes a first clamping plate 11 and a second clamping plate 12 for clamping the composite material plate 2 from the upper and lower sides. The first clamping plate 11 and the second clamping plate 12 both include an elongated lug plate 17 and a threaded transition plate 18 connected to the inner side of the elongated lug plate 17. The threaded transition plate 18 has multiple rows of metal threads 13 pre-machined on it, and the spacing of the multiple rows of metal threads 13 is less than a preset value. The metal threads 13 are disposed on the surface of the threaded transition plate 18 on the adjacent sides of the first clamping plate 11 and the second clamping plate 12.

[0047] The composite material plate 2 has composite threads 21 on both its upper and lower surfaces that match the metal threads 13, wherein the height of the metal threads 13 is [missing information]. h The thread has a fine thread diameter (between 0.5 mm and 1.5 mm) and a tooth angle of 30° to 60°. The first clamping plate 11 and the second clamping plate 12 can clamp the composite material plate 2 together via a fastening connector 3. The fastening connector 3 consists of a fastening screw 31 and a fastening nut 32. A threaded engagement interface 4 is provided between the metal clamping plate 1 and the composite material plate 2. Figure 4 As shown, the thread engagement interface 4 is composed of a metal thread 13 and a composite thread 21.

[0048] In one specific embodiment, combined with Figure 5 The transverse arrangement of the metal threads 13 in the first clamping plate 11 and the second clamping plate 12 is either parallel transverse threads 131 or parallel oblique threads 132, and they are fine threads such as triangular threads or sawtooth threads, which are manufactured using conventional machining equipment. Combined with Figure 6 The first clamping plate 11 and the second clamping plate 12 are used to place the composite material plate 2 that needs to be connected and clamped between their surfaces with metal threads 13.

[0049] Combination Figure 5 and Figure 6The outer ends of the first clamping plate 11 and the second clamping plate 12 are provided with connecting pin holes 16 (for connection with connecting pin holes 16 on another metal clamping plate 1 via pin shafts), and the inner ends are provided with threaded transition plates 18 and gentle chamfers 19. Fastening ear plates 14 are provided on both sides of the lateral side of the metal thread 13 area on the threaded transition plates 18 of the first clamping plate 11 and the second clamping plate 12. The fastening ear plates 14 are provided with a plurality of fastening screw holes 15, which are arranged longitudinally at intervals on the fastening ear plates 14. Both the elongated ear plate 17 and the fastening ear plate 14 are higher than the thickness of the plate material in the area of ​​the metal thread 13. When the composite material plate 2 is placed between the first clamping plate 11 and the second clamping plate 12, the elongated ear plate 17 and the fastening ear plates 14 on both sides are used to abut against the ends of the composite material plate 2 to achieve longitudinal and lateral limiting of the composite material plate 2. In this limiting state, the longitudinal axis of the composite material plate 2 and the metal clamping plate 1 coincides, and the extension direction of each row of metal threads 13 intersects with the longitudinal axis. The fastening screw hole 15 is used to press down the first clamping plate 11 to press the upper and lower sides of the composite material plate 2 to form the composite material thread 21 and its thread engagement interface 4 with the metal thread 13. Then, the fastening connector 3 is screwed in first to fix the composite material plate 2 and the metal clamping plate 1. Then, the fastening connector 3 is tightened according to the preset fastening force to generate pre-compression stress at the thread engagement interface 4 to complete the assembly connection of the composite material plate 2.

[0050] like Figure 7 , Figure 8 and Figure 9 As shown, the composite thread 21 is formed by the mechanical ballast device 6 pressing the upper first clamping plate 11, causing the first clamping plate 11 and the second clamping plate 12 to press the metal thread 13 into the outer wall of the composite material plate 2 from both the top and bottom. Figure 10 As shown, to prevent the mechanical ballast device 6 from laterally crushing and damaging the composite material plate 2 during the forming process of the composite thread 21, anti-overpressure limiting blocks 5 are provided on both outer edges of the composite material plate 2 and between the metal clamping plate 1. Their thickness is approximately twice the height of the metal thread 13 (i.e., 2). h ).

[0051] Specifically, the working principle of Embodiment 1 of a press-fit dense threaded connection structure for composite material plates is as follows: First, the composite material plate 2 is pre-positioned. The second clamping plate 12, which has been pre-processed with metal threads 13, is placed on the lower plate of the mechanical ballast device 6. The end of the composite material plate 2 without composite threads 21 is placed on the second clamping plate 12, and the first clamping plate 11 is fastened to the composite material plate 2. The side of the composite material plate 2 is against the fastening ear plates 14 of the first clamping plate 11 and the second clamping plate 12 to achieve lateral limitation. The end is against and aligned with the elongated ear plates 17 of the first clamping plate 11 and the second clamping plate 12 to achieve longitudinal limitation. In this limiting state, the longitudinal axis of the composite material plate 2 and the metal clamping plate 1 coincides, and the extension direction of each row of metal threads 13 intersects with the longitudinal axis. In this embodiment, the pre-positioning of the composite material plate 2 provides the prerequisite for the subsequent pressing and forming of composite threads.

[0052] Then, the composite material plate 2 is kept in a predetermined position and a pressure-limiting block 5 is placed above the ear plates 14 on both sides of the second clamping plate 12 to limit the downward stroke, so as to prevent the composite material plate 2 from being crushed and damaged during the molding of the composite thread 21.

[0053] Further, a threaded engagement interface 4 is generated. The first clamping plate 11 is pressed down by the mechanical ballast device 6 so that the metal threads 13 on the first clamping plate 11 and the second clamping plate 12 are gradually pressed into the upper and lower sides of the composite material plate 2. After the metal threads 13 are completely embedded in the outer wall of the composite material plate 2, the pressure is maintained for a preset time and then unloaded, forming the composite thread 21 and the threaded engagement interface 4 composed of the composite thread 21 and the metal thread 13. It should be noted that in this embodiment, a smaller metal thread 13 (the spacing between multiple rows of metal threads 13 is less than 3.0 mm, and the height of the metal thread 13 is 0.5 mm to 1.5 mm) and a composite thread 21 are used at the thread engagement interface 4. This significantly reduces the longitudinal continuous fiber damage amplitude and cross-sectional attenuation rate, ensuring connection strength and load-bearing efficiency. The numerous and clustered composite threads 21 can enhance the reliability of the joint and avoid the insufficient connection performance caused by a small number of discrete teeth. The root of the composite thread 21 has a gentle angle, which can improve the stress concentration problem caused by the rectangular teeth of the composite material and reduce the local peak shear stress of the composite material, thereby improving the overall strength of the joint. The composite thread 21 can directly avoid its own transverse crushing failure during the molding process, thus it can apply a larger fastening force and interface pre-compression stress, which can significantly enhance the interlaminar shear strength of the composite material and further improve the connection strength and load-bearing efficiency of the joint. Furthermore, the composite thread 21 of this invention is passively formed by pressing the metal thread 13 on the ballast metal clamping plate 1. The gap between the metal thread 13 and the composite thread 21 on the thread engagement interface 4 is negligible, which avoids problems such as groove defects and gap errors caused by pre-cutting composite material grooves. This ensures the consistency between the actual finished product and the structural design, and the product quality is controllable. This invention allows for flexible setting of the number, shape, and size of the composite thread 21, as well as the length of the thread engagement interface 4 section, resulting in strong design flexibility for load-bearing capacity. This embodiment does not rely on the interlayer shear force provided by the adhesive for force transmission, but rather on the mechanical interlocking of threads of different materials on the thread engagement interface 4 to transmit axial force, ensuring durability in complex environments and long-term load use.

[0054] Finally, after installing the fastening connector 3 and generating the threaded engagement interface 4, the first clamping plate 11, the second clamping plate 12, and the composite material plate 2 remain in their original positions. Remove the overpressure limiting block 5 and screw the fastening connector 3 into the fastening screw hole 15 to fix the composite material plate 2 and the metal clamping plate 1 together. According to the design value, tighten the fastening connector 3 in a preset cross sequence to generate pre-compression stress at the threaded engagement interface 4 to complete the assembly connection of the composite material plate 2 and the metal clamping plate 1, thereby realizing the integrated design of the molding process and the connection structure.

[0055] After the press-fit threaded connection structure is assembled, when one end of the joint is subjected to an axial load, the concentrated axial force is first transmitted to the elongated ear plate 17 through the connecting pin hole 16 at the end of the metal clamping plate 1, then to the threaded transition plate 18, and then to the composite material plate 2 through the threaded engagement interface 4, and finally to the joint at the other end. Among them, the threaded engagement interface 4 mainly relies on the shearing action of the composite thread 21 to transmit the axial force, with a clear force transmission path and good effect. Example 2

[0056] This embodiment provides an assembly method for a press-fit dense threaded connection structure for composite material plates. The method is based on the aforementioned press-fit dense threaded connection structure for composite material plates, such as... Figures 11 to 15 As shown. The method includes: Step 1: Prepare each metal component according to the design dimensions, and use machining technology to complete the processing of the first clamping plate 11, the second clamping plate 12, the fastening connector 3 and the overpressure limit block 5.

[0057] Step 2: Prepare the solid composite material board 2 according to the design dimensions. The reinforcing fiber can be glass fiber, carbon fiber, basalt fiber, etc. It is made by processes such as pultrusion, winding, hand lay-up, molding, vacuum-assisted, 3D printing, liquid molding, etc. The finished product is cut to the designed length using a cutting machine.

[0058] Step 3: Based on the detailed design dimensions of the metal thread 13, the metal thread 13 (the spacing between multiple rows of metal threads 13 is less than 3.0 mm, and the height of the metal thread 13 is 0.5 mm to 1.5 mm) at the ends of the first clamping plate 11 and the second clamping plate 12 is prepared using conventional machining processes. The configuration is a fine thread such as a triangular thread or a sawtooth thread, and the transverse arrangement is a parallel transverse thread 131 or a parallel oblique thread 132.

[0059] Step 4: Place the second clamping plate 12 on the lower plate of the mechanical ballast device 6, then accurately place the composite material plate 2 between the fastening ear plates 14 on both sides of the second clamping plate 12, and then place the first clamping plate 11 on the composite material plate 2. During the placement process, it is necessary to ensure that the end of the composite material plate 2 is aligned with the end of the threaded transition plate 18, and that the longitudinal axes of each component coincide.

[0060] Step 5: Install overpressure limiting blocks 5 on the upper part of the fastening ear plates 14 on both sides of the first clamping plate 11 (i.e., the outer edges of both sides of the composite material plate 2) to prevent the composite material plate 2 from being crushed and damaged during the molding of the composite thread 21.

[0061] Step 6: Start the mechanical ballast device 6 and gradually press the metal threads 13 of the first clamping plate 11 and the second clamping plate 12 into the composite material plate 2. After the metal threads 13 are completely embedded in the outer wall of the composite material plate 2, the loading end of the mechanical ballast device 6 maintains pressure for about 1 minute and then unloads, thus completing the forming of the composite material thread 21 and the thread engagement interface 4.

[0062] Step 7: Keeping the spatial positions of the first clamping plate 11, the second clamping plate 12 and the composite material plate 2 unchanged, install the fastening connectors 3 in the fastening screw holes 15 on both sides of the metal clamping plate 1 to complete the tight connection and position fixation between the metal clamping plate 1 and the composite material plate 2.

[0063] Step 8: Remove the overpressure limit block 5; according to the design value of the tightening force, use a conventional torque wrench and tighten the fastening connector 3 in a symmetrical cross sequence (such as diagonal → adjacent cycle) to make the metal clamp plate 1 and the composite material plate 2 form a solid whole, and complete the assembly of the entire press-fit threaded connection structure. Example 3

[0064] This embodiment provides another assembly method for a press-fit type dense threaded connection structure for composite material plates, based on the aforementioned press-fit type dense threaded connection structure for composite material plates. The difference from Embodiment 2 is that the composite material plate 2 is a hollow plate. To prevent it from being laterally crushed during the forming process of the composite thread 21, a metal liner 7 is required in its inner cavity for radial support, such as... Figures 16 to 15 As shown. The difference between this embodiment and Embodiment 2 lies only in step two, specifically: Step 2: Prepare the hollow composite material plate 2 according to the design dimensions. The reinforcing fiber can be glass fiber, carbon fiber, basalt fiber, etc., and it is made by processes such as pultrusion, winding, hand lay-up, molding, vacuum-assisted, 3D printing, liquid molding, etc. The finished product is cut to the designed length using a cutting machine. A metal liner 7 with a matching shape and a slightly larger outer diameter needs to be set in the inner cavity of the composite material plate 2. The metal liner 7 is placed in the inner cavity of the composite material plate 2 using liquid nitrogen cooling method.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A press-fit threaded connection structure for composite material plates, comprising composite material plates, characterized in that, Also includes: A metal clamp for connecting the ends of a composite material plate in the longitudinal direction, the metal clamp including a first clamp and a second clamp for clamping the composite material plate from the upper and lower sides. Both the first clamping plate and the second clamping plate include: The long oval ear plate and the threaded transition plate connected to the inner side of the long oval ear plate are provided. The long oval ear plate has a connecting pin hole. The threaded transition plate is pre-machined with multiple rows of metal threads. The spacing between the multiple rows of metal threads is less than a preset value. Fastening ear plates are provided on both sides of the metal thread area of ​​the threaded transition plate. Both the elongated ear plates and the fastening ear plates are higher than the thickness of the metal thread area plate. When the composite material plate is placed between the first clamping plate and the second clamping plate, the elongated ear plates and the fastening ear plates on both sides are used to abut against the ends of the composite material plate to achieve longitudinal and lateral limiting of the composite material plate. In this limiting state, the longitudinal axis of the composite material plate and the metal clamping plate coincides, and the extension direction of each row of metal threads intersects with the longitudinal axis. Fastening screw holes are provided on the fastening ear plates on both sides and arranged longitudinally at intervals; the fastening screw holes are used to press down the first clamping plate to press the upper and lower sides of the composite material plate to form the composite material thread and the thread engagement interface between the composite material thread and the metal thread, and then screw in the fastening connector to fix the composite material plate and the metal clamping plate. Then, the fastening connector is tightened according to the preset fastening force to generate pre-compression stress at the thread engagement interface to complete the assembly connection of the composite material plate.

2. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, Also includes: Before the first clamping plate is pressed down, an overpressure limiting block needs to be placed on the fastening ear plates on both sides of the second clamping plate. The thickness of the overpressure limiting block is greater than the height of the metal thread.

3. The press-fit threaded connection structure for composite material plates according to claim 2, characterized in that, The thickness of the overpressure protection limit block is twice the height of the metal thread.

4. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, The metal thread is a fine thread with a tooth angle of 30° to 60°, and the metal thread includes triangular threads or sawtooth threads.

5. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, The metal thread includes a parallel transverse thread or a parallel oblique thread.

6. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, The threaded transition plate has a gentle chamfer on its inner end away from the elongated ear plate.

7. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, The spacing between multiple rows of metal threads is less than 3.0 mm.

8. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, The height of the metal thread is 0.5 mm to 1.5 mm.

9. The press-fit threaded connection structure for composite material plates according to claim 1, characterized in that, The composite material plate is a rectangular plate; The composite material plate can be hollow or solid. If the composite material plate is hollow, a metal liner needs to be installed inside the cavity of the composite material plate.

10. An assembly method for a press-fit threaded connection structure for composite material plates, characterized in that, The assembly method, applied to the press-fit type threaded connection structure according to any one of claims 1-9, comprises: Pre-positioning of composite material plate: The second clamping plate with pre-machined metal threads is placed on the lower plate of the mechanical ballast equipment. The end of the composite material plate without composite material threads is placed on the second clamping plate and the first clamping plate is fastened to the composite material plate. The side of the composite material plate is against the fastening lugs of the first and second clamping plates to achieve lateral positioning. The end is against and aligned with the elongated lugs of the first and second clamping plates to achieve longitudinal positioning. In this positioning state, the longitudinal axes of the composite material plate and the metal clamping plate coincide, and the extension direction of each row of metal threads intersects the longitudinal axis. Overpressure limiting blocks are set: the composite material plate remains in a pre-positioned limiting state, and overpressure limiting blocks are placed above the fastening ear plates on both sides of the second clamping plate to limit the downward stroke, so as to prevent the composite material plate from being crushed and damaged during the composite thread forming process. Generate thread engagement interface: The first clamping plate is pressed down by a mechanical ballast device so that the metal threads on the first and second clamping plates are gradually pressed into the upper and lower sides of the composite material plate. After the metal threads are fully embedded in the outer wall of the composite material plate, the pressure is maintained for a preset time and then unloaded, forming composite material threads and thread engagement interface composed of composite threads and metal threads. Install fastening connectors: After the threaded engagement interface is generated, the first clamping plate, the second clamping plate, and the composite material plate remain in the same position. Remove the overpressure limit block and screw the fastening connectors into the fastening screw holes to fix the composite material plate and the metal clamping plate together. Apply lateral fastening force: According to the design value, tighten the fastening connectors in a preset cross sequence to generate pre-compression stress at the thread engagement interface to complete the assembly connection of the composite material plate and the metal clamp.

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