A low-probe and pneumatic integrated telescopic hexagonal groove countersunk screw

Abstract

The utility model discloses a low scattering and pneumatic integrated telescopic hexagonal groove countersunk head screw, it includes screw cap, countersunk head round platform thread and stem. Screw cap includes six prismatic marbles spring and six prismatic inner groove, when not considering the tolerance gap between six prismatic marbles and six prismatic inner groove, the stem is the cylinder that is connected with the bottom surface of screw cap, and the thread is the ordinary thread that is equidistantly surrounded in the stem, that is, the triangular tooth shape. The low scattering pneumatic telescopic hexagonal groove countersunk head screw provided by the utility model provides the design principle of low scattering pneumatic screw radar stealth and pneumatic shape, which is a design method for the comprehensive mechanical properties of the low detectability of the screw pneumatic, and the design idea is unique and ingenious, the pneumatic low detectability effect is remarkable, the mechanical properties are good, and the design part has high universality. It can be operated and used by using the general hexagonal screwdriver, and it is convenient to couple all the screws with the whole in the gap direction.

Description

Technical Field

[0001] This invention belongs to the field of low scattering and aerodynamic integration technology, specifically a telescopic hexagonal countersunk screw, which can be used to reduce the detectability of weak scattering sources such as screws and rivets in weapon equipment and improve their aerodynamic performance. Background Technology

[0002] Low-observable technology effectively reduces the probability of a target being detected, identified, tracked, and attacked, thereby improving its battlefield survivability and making it the most important penetration tactic in modern warfare. In medium- and long-range air combat, the stealth threat to aircraft primarily comes from electromagnetic detectors. The radar cross section (RCS) is a key indicator characterizing the ability of a stealthy target to scatter incident waves. For conventional aircraft, in addition to the three major strong scattering sources—radar bay, cockpit, and air intake—gaps, steps, and fastening rivets and screws at infrequently opened covers can create electrical discontinuities, which are the main scattering sources affecting the overall stealth performance after the strong scattering sources are effectively reduced. Currently, screws are mainly round-headed Phillips head countersunk screws; the total RCS of more than ten 10mm diameter round-headed screws can reach 1m. 2 Therefore, it is evident that scattering reduction and suppression from weak scattering sources such as screws and rivets are crucial for improving the low observability of weapons and equipment. Current research on weak scattering sources such as screws and rivets mainly focuses on qualitatively analyzing their impact on the overall low observability of weapons and equipment from the perspective of scattering mechanisms, without addressing scattering reduction design or quantitative RCS analysis, making it difficult to further improve the overall low observability of targets.

[0003] Furthermore, for aircraft and other weaponry, high speed and high maneuverability place higher demands on their aerodynamic performance. Aerodynamic optimization design technology can effectively reduce the drag caused by fluid resistance during movement, thereby reducing energy consumption and improving maneuverability. Typically, aircraft aerodynamic design focuses on the shape of each wing surface (main wing, horizontal and vertical tail, etc.) and its layout on the aircraft. However, small protrusions on the aircraft wings, such as rivets, screws, and bolts, while connecting various parts of the wing, also contribute to reducing aerodynamic drag during flight. Aircraft often use countersunk rivets, where the nose is completely embedded below the surface of the connecting parts. The smooth and flat contact surfaces between the connecting parts reduce airflow separation and disturbance, not only reducing aerodynamic drag but also further improving the aircraft's aesthetic appearance. Research data from World War II shows that using countersunk rivets can reduce aircraft aerodynamic drag by approximately 3%. Therefore, the impact of non-critical aerodynamic components such as screws and rivets on the overall aerodynamic drag of the aircraft is not negligible.

[0004] With the continuous improvement of combat technology in various countries, the integration of aerodynamics and stealth is essential for current weapons and equipment. In particular, for components such as screws and rivets, which have relatively small scattering and aerodynamic impact on the entire weapon system, the design of stealth and aerodynamic integration is still in its infancy. To address this issue, this utility model proposes a retractable hexagonal countersunk screw with both low detectability and low aerodynamic drag. Summary of the Invention

[0005] The purpose of this invention is to provide a low-detectability and pneumatically integrated screw to further reduce the detectability of traditional screws to electromagnetic detectors and their impact on aerodynamic performance, eliminate their influence as a weak scattering source, and further improve the overall aerodynamic performance of the vehicle.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0007] A low-scattering pneumatic telescopic hexagonal countersunk screw, as shown in Figure 1, consists of a stealthy pneumatic integrated head and a screw. The stealthy pneumatic integrated screw head is a frustum nut with a hexagonal groove inside. The projection of the hexagonal groove on the upper surface of the screw head is a regular hexagon.

[0008] As shown in Figure 2, a hexagonal inner groove contains a spring and a hexagonal ball. The bottom of the spring is fixedly connected to the bottom of the groove by resistance welding, and the top of the spring is fixedly connected to the bottom of the hexagonal ball by resistance welding. The outer diameter side of the spring is in contact with the inner wall of the hexagonal groove. The ball is a regular hexagonal frustum to fit into the hexagonal inner groove, and its top is on the same horizontal plane as the top of the screw head.

[0009] The head cross-section is shown in Figure 3. The head is a frustum-shaped nut with a hexagonal inner groove inside. A spring and a hexagonal pin are housed within the groove. Both the hexagonal inner groove and the hexagonal pin have regular hexagonal bottom projections. They are engaged by the spring within the groove. When not being tightened, the upper surface of the hexagonal pin is flush with the upper surface of the nut head. When tightening, the hexagonal screwdriver engages with the inner surface of the hexagonal inner groove. Applying pressure to the hexagonal pin compresses the spring, allowing the low-scattering telescopic hexagonal countersunk screw to be tightened. At this point, the upper surface of the pin is lower than the upper surface of the nut head. After tightening, the hexagonal screwdriver withdraws from the hexagonal inner groove, and the hexagonal pin returns to its original position under the spring force, its upper surface once again being flush with the upper surface of the screw and nut. The gap between the hexagonal pin and the hexagonal inner groove should be as small as possible; the smaller the gap, the better the low-scattering and aerodynamic performance.

[0010] As shown in Figure 1, the screw is fixedly connected to the bottom surface of the stealth pneumatic integrated head nut, and the whole is a cylinder.

[0011] The thread, as shown in Figure 1, is a general-purpose thread, with equal intervals around the screw.

[0012] This utility model has the following advantages:

[0013] 1. This utility model proposes a stealth aerodynamic integrated retractable hexagonal countersunk screw structure, which not only considers the practicality of screw design, but also takes into account low detectability and aerodynamics, which is conducive to further reducing the scattering and aerodynamic drag of aircraft, etc., and improving their stealth and aerodynamic performance.

[0014] 2. The design method proposed in this utility model can provide grooves and balls of specified shapes, such as triangles or rhombuses, according to actual engineering needs. It is a general design method with flexible design and significant effects.

[0015] Theoretical analysis shows that, under horizontal and vertical polarization, for incident electromagnetic waves within the [0, 360°] range, the low-scattering and aerodynamically integrated hexagonal countersunk screw designed in this invention exhibits a significantly reduced RCS compared to traditional Phillips head countersunk screws, and the surface gas friction resistance is also reduced. From a design perspective, this invention solves the problems of strong scattering and poor aerodynamic performance in existing screws. Attached Figure Description

[0016] Figure 1 is a schematic diagram of the low-scattering and aerodynamic integrated hexagonal slot countersunk screw structure;

[0017] Figure 2 is a top view of the low-scattering and aerodynamic integrated hexagonal slot countersunk screw structure;

[0018] Figure 3 is a side cross-sectional view of the low-scattering and aerodynamic integrated hexagonal slot countersunk screw structure.

[0019] Labeling explanations: 1. Hexagonal ball; 2. Nut; 3. Countersunk frustum; 4. Thread; 5. Rod; 6. Spring; 7. Hexagonal groove. Detailed Implementation

[0020] This utility model relates to a design method for a low-scattering and pneumatically integrated telescopic hexagonal countersunk screw, applicable to the design of screw low-scattering and pneumatically integrated structures. To explain in detail the technical content, structural features, and achieved objectives and effects of this utility model, specific implementation methods and design approaches are combined for illustration:

[0021] Referring to Figure 1, this utility model includes a head 2, a screw 5, and a thread 4; the head (excluding the screw) has a height of 4.3 mm; the screw 5 is a cylinder connected to the regular n-sided polygon at the bottom of the head, with a height of 6.94 mm; the thread 4 is a common thread (i.e., triangular tooth profile), with a tooth profile angle of 60°, and is evenly spaced around the rod body with a spacing of 0.9 mm.

[0022] Step 1: Design the upper surface shape of the head. Based on the mirror scattering mechanism and the gas friction resistance mechanism, when the screw groove is blocked, the electromagnetic defects caused by the weak scattering source will basically disappear, meaning the screw has low detectability. Since the groove is isolated, no contact occurs, and the gap between the insulator and the upper surface of the screw is negligible compared to the original groove size, thus it has relatively strong aerodynamic performance. Because the hexagonal design of the hexagonal screw prevents loosening, thereby increasing the stability of the connection and facilitating installation and disassembly, considering the practicality of screw connection engineering, the low-scattering and aerodynamic integrated screw head is projected as a regular hexagon in the horizontal plane. Furthermore, to further reduce gas friction resistance, the contact surface between the screw head and the gas should be as smooth as possible; therefore, the upper surface of the head is designed as a single plane. Referring to Figure 3, the head 2 includes a hexagonal tumbler 1, a spring 6, and a hexagonal inner groove 7. The bottom projections of the hexagonal inner groove and the hexagonal tumbler are both regular hexagons. This utility model is a retractable, low-scattering, and pneumatically integrated hexagonal countersunk screw. When the tolerance clearance between the hexagonal inner groove and the hexagonal ball is sufficiently high, the upper surface of the nut can be equivalent to a single plane.

[0023] Referring to Figure 2, the head 2 has an embedded groove 3 and a spring 6. Step 2: Define the dimensions of the hexagonal inner groove and the hexagonal ball in the head.

[0024] The depth of the hexagonal recess in a screw should be determined by comprehensively considering the screw's mechanical properties. An excessively deep recess can lead to breakage at the connection between the screw and the nut, while a shallow recess results in insufficient contact area between the screwdriver and the screw, leading to insufficient tightening torque and potential damage to the nut and stripping of the threads. Taking an M8 countersunk hexagonal socket screw as an example, based on experimental and simulation results, the designed depth of the hexagonal recess is 3mm, with a side length of 3.46mm for the horizontal projection of the recess. The hexagonal ball is placed within the recess, therefore its hexagonal dimensions in the horizontal projection should be within the machining tolerance range. For example, with a machining accuracy of 0.01mm, the side length of the hexagon in the horizontal projection is 3.45mm, and the thickness is 0.5mm.

[0025] Step 3, specify the dimensions of the spring in the hexagonal groove of the head.

[0026] The spring is positioned directly below the hexagonal tumbler and connected to the bottom of the hexagonal groove. Based on the depth of the groove and the thickness of the tumbler, the spring in the groove should ensure that the upper surface of the hexagonal tumbler is flush with the upper surface of the nut when naturally extended; therefore, its height during natural extension should be 2.5mm. To prevent the hexagonal tumbler from being thrown out or pressed too deeply into the groove during maneuvering overloads, which could affect the aircraft's stealth and aerodynamic performance and increase the difficulty of ground maintenance, the spring force is designed to be 3N based on simulation experiments. The hollow circle on the spring's horizontal projection surface has an outer diameter of 6mm, an inner diameter of 5.8mm, and a spring tube diameter of 0.1mm, tangent to the vertical plane of the hexagonal groove. When the spring is fully compressed, its height is 0.5mm.

[0027] Step 4, give the screw rod

[0028] The screw shank is a cylinder connected to the circular bottom surface of the frustum head, with the same height as a traditional Phillips head countersunk screw.

[0029] Step 5, specify the screw thread

[0030] The screw thread is a plain thread with equal spacing, and the pitch and thread type are the same as those of international standard screws.

Claims

1. A low detectable and aerodynamic integrated retractable hex socket flat head screw, characterized in that Includes nut (2), countersunk frustum (3), thread (4), and rod (5): The nut (2) includes a hexagonal ball (1), a spring (6), and a hexagonal groove (7): The rod body (5) is a cylinder connected to the circular bottom surface of the nut; A standard thread (4) is wrapped around the shaft (5).

2. The low-detectability and pneumatically integrated telescopic hexagonal countersunk screw according to claim 1, characterized in that... The nut (2), the rod (5) and the ordinary thread (4) are exposed to electromagnetic and airflow environments on only one surface. According to the mirror scattering and gas friction resistance mechanism and the requirements of low RCS and low resistance, one surface meets the low detectability condition and low resistance condition of the minimum RCS angle peak.

3. The low-detectability and pneumatically integrated telescopic hexagonal countersunk screw according to claim 1, characterized in that... The hexagonal ball (1) and the hexagonal groove (7) are characterized in that their horizontal projections are both regular hexagons.

4. The low-detectability and pneumatically integrated telescopic hexagonal countersunk screw according to claim 1, characterized in that... The top and bottom of the spring (6) are respectively attached to and fixed to the bottom of the hexagonal ball (1) and the bottom of the hexagonal inner groove (7). The outer diameter circle of the spring (6) is inscribed in the regular hexagon of the horizontal projection of the vertical plane of the hexagonal inner groove (7).

5. The low-detectability and pneumatically integrated telescopic hexagonal countersunk screw according to claim 1, characterized in that... The specific dimensions of the hexagonal ball (1) and the hexagonal groove (7) should be determined according to the required internal hexagon screw specifications for the given real-world scenario.

6. The low-detectability and pneumatically integrated telescopic hexagonal countersunk screw according to claim 1, characterized in that... The ordinary thread (4) is evenly spaced around the rod body (5), and the thread spacing is determined according to the required internal hex screw specifications for the application scenario.

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