Anti-tamper screws

Abstract

This application relates to the field of fastener technology, and more particularly to an anti-tamper screw. It includes: a screw shank, a screw head, and a central island and a groove surrounding the central island on the end face of the screw head away from the screw shank. At least one sidewall of the groove has a first protrusion, reducing the width of the groove at the first protrusion. The screw head is at least partially tapered in a conical shape along the direction away from the screw shank. The first protrusion on the sidewall of the groove reduces the width of the groove at the protrusion. Conventional screwdrivers, because their head width is greater than the width at the protrusion, cannot fully insert into the groove, causing slippage when force is applied and preventing effective screw rotation. The presence of the central island further reduces the effective operating space of the groove, allowing only specialized tools to be inserted and force applied, significantly increasing the anti-tamper threshold.

Description

Technical Field

[0001] This application relates to the field of fastener technology, and more particularly to an anti-tamper screw. Background Technology

[0002] Currently, all electrical products on the market require the use of protective housings. These housings are mostly assembled and fixed using screws. In daily use, to ensure user safety and avoid warranty disputes, these electrical products need to use tamper-proof screws to prevent non-professionals from disassembling them themselves.

[0003] The principle of tamper-proof screws is that the screw head groove is designed with a special shape so that the head of a regular screwdriver cannot match the screw groove. When the screwdriver is turned, it cannot transmit torque to the screw, thus achieving tamper-proof screw.

[0004] Currently, a common design method for tamper-proof screws is to install a cylindrical rod in the center of the standard internal pentagonal, internal hexagonal, or internal six-pointed star grooves to prevent the corresponding screwdriver head from being inserted into the groove. This type of tamper-proof screw has the disadvantage of being easy and inexpensive to remove: when a standard screwdriver is used to apply impact force to the central rod, the central rod can be easily chipped away, and the screw can then be removed with a standard screwdriver. Another common design method for tamper-proof screws is to design triangular, square, H-shaped, and Y-shaped grooves. The disadvantage of this type of tamper-proof screw is that it can be easily removed by simply modifying the head of a standard screwdriver. For example, tamper-proof screws with triangular or square grooves can be removed by filing and grinding the head of a standard screwdriver into a triangle or square shape; tamper-proof screws with H-shaped grooves can be removed by filing or grinding a small notch in the center of the head of a flathead screwdriver. Y-shaped groove tamper-proof screws can be bypassed by inserting a flathead screwdriver of appropriate width into the groove at the head of the screw. This type of easily bypassed tamper-proof screw has a low technical barrier and low cost, making it easy to implement and thus rendering the tamper-proof screw ineffective. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this application provides an anti-disassembly screw.

[0006] This application provides an anti-tamper screw, comprising:

[0007] Screw rod,

[0008] A screw head is disposed at one end of the screw rod, and the end face of the screw head away from the screw rod is provided with a central island platform and a groove surrounding the central island platform. At least one side wall of the groove is provided with a first protrusion to reduce the width of the groove at the first protrusion. The screw head is at least partially configured as a tapered cone in the direction away from the screw rod.

[0009] In some embodiments, a neck is formed between the two ends of the groove along the circumferential direction, the neck isolating the two ends of the groove from each other along the circumferential direction.

[0010] In some embodiments, the angle between the outer circumferential surface of the screw head and the end face of the screw head away from the screw rod is α, where 45° < α < 75°.

[0011] In some embodiments, at least one of the inner and outer sidewalls of the groove is inclined, and the included angle between the inner and outer sidewalls is β, where β > 5°.

[0012] In some embodiments, the width of the groove opening is L, and the width of the groove bottom is M, where L ≥ 0.5 mm.

[0013] In some embodiments, the groove is C-shaped.

[0014] In some embodiments, the height of the first protrusion protruding into the groove is H, where H > L / 3.

[0015] In some embodiments, the number of the first protrusions is multiple, and the multiple first protrusions are spaced apart circumferentially along the groove.

[0016] In some embodiments, the screw head includes a first connecting segment and a second connecting segment, wherein the outer circumferential surface of the first connecting segment is a cylindrical surface and the circumferential surface of the second connecting segment is a gradually tapering conical surface.

[0017] In some embodiments, the axial height of the first connecting segment is less than 1 mm.

[0018] The technical solution provided in this application has the following advantages compared with the prior art:

[0019] The tamper-proof screw provided in this application embodiment features a first protrusion on the sidewall of the groove that reduces the width of the groove at the protrusion. Conventional screwdrivers, with heads wider than the protrusion, cannot fully embed into the groove, causing slippage during force application and preventing effective screw rotation. The presence of the central island further reduces the effective operating space of the groove, allowing only specialized tools (matching the groove shape) to embed and apply force, significantly raising the tamper-proof threshold. The tapered circumferential surface of the screw head prevents common clamping tools (such as wrenches and pliers) from stably holding the screw head, further blocking unauthorized disassembly. This tamper-proof screw, through a dual tamper-proof mechanism—the first protrusion on the sidewall of the groove restricting tool embedding and the tapered surface blocking tool adaptation—solves the problem of traditional screws being easily disassembled by common tools. Furthermore, the combination of the first protrusion and the central island makes the tamper-proof structure difficult to damage, resulting in strong tamper-proof performance, a simple and reliable structure, and wide applicability. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the anti-tamper screw described in an embodiment of this application;

[0023] Figure 2 This is a top view of the tamper-proof screw described in the embodiment of this application;

[0024] Figure 3 for Figure 2 Sectional view along line AA;

[0025] Figure 4 for Figure 3 A magnified view of point A in the middle.

[0026] Among them, 1. Screw rod;

[0027] 2. Screw head; 21. Groove; 22. Central island; 23. Neck; 201. Second connecting section; 202. First connecting section; 211. First protrusion. Detailed Implementation

[0028] To better understand the above-mentioned objectives, features, and advantages of this application, the solution of this application will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of this application, but this application may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of this application, and not all embodiments.

[0030] Related technologies involve designing triangular, square, H-shaped, and Y-shaped grooves on tamper-proof screws. By simply grinding and shaping a regular screwdriver tip, the tamper-proof screws can be bypassed, resulting in poor tamper-proof performance.

[0031] To solve this technical problem, such as Figures 1 to 4 As shown, this application embodiment provides an anti-tamper screw, including: a screw rod 1 and a screw head 2. The screw rod 1 is provided with external threads for threaded connection with a fastener. The screw head 2 is disposed at one end of the screw rod 1, and the end face of the screw head 2 away from the screw rod 1 is provided with a central island platform 22 and a groove 21 surrounding the central island platform 22. At least one side wall of the groove 21 is provided with a first protrusion 211 to reduce the width of the groove 21 at the first protrusion 211. The screw head 2 is at least partially configured as a tapered cone in the direction away from the screw rod 1.

[0032] Specifically, the end face of the screw head 2 away from the screw rod 1 is originally a flat or curved surface. A groove 21 is formed on this end face, with the groove 21 centered on the center line of the end face, thus forming a central island 22 at the center of the end face. The shape of the groove 21 can be C-shaped, semi-circular, non-closed rectangular, or triangular, etc. The groove 21 has an inner wall and an outer wall. The inner wall is the side wall closer to the center of the screw head 2, and the outer wall is the side wall away from the center of the screw head 2. The outer wall and the inner wall are arranged opposite to each other. Since the central island 22 is formed when the groove 21 is formed, the outer wall of the central island 22 also forms the inner wall of the groove 21. A first protrusion 211 is provided on the outer wall and / or inner wall of the groove 21, and the width of the groove 21 decreases at the first protrusion 211.

[0033] The circumferential surface of the screw head 2 is at least partially tapered in the direction away from the screw shank 1, resulting in a cone shape where one end is larger than the other. Because the tapered circumferential surface is inclined, when using tools such as wire cutters to clamp the screw head, the wire cutters will slip on the screw head, making it difficult for such tools to clamp the screw head, thereby improving the anti-tampering level of the anti-tamper screw.

[0034] The tamper-proof screw provided in this embodiment reduces the width of the groove 21 at the protrusion by a first protrusion 211 on the sidewall of the groove 21. Conventional screwdrivers, due to the mismatch between the head width and thickness and the protrusion's width and thickness, cannot fully embed themselves in the groove 21, or slip when force is applied, thus preventing effective screw rotation. The presence of the central island 22 further reduces the effective operating space of the groove 21, allowing only specialized tools (matching the shape of the groove 21) to embed and apply force, significantly raising the tamper-proof threshold. The tapered circumferential surface of the screw head 2 prevents general-purpose clamping tools (such as wrenches and pliers) from stably clamping the screw head 2, further blocking illegal disassembly. This tamper-proof screw, through a dual tamper-proof mechanism—the first protrusion 211 on the sidewall of the groove 21 restricting tool embedding and the tapered surface blocking the clamping tool—solves the problem of traditional screws being easily disassembled by general-purpose tools. Furthermore, the combination of the first protrusion 211 and the central island 22 makes the tamper-proof structure difficult to damage, resulting in strong tamper-proof performance, simple and reliable structure, and wide applicability.

[0035] In some embodiments of this application, a neck 23 is formed between the two ends of the groove 21 along the circumferential direction, and the neck 23 isolates the two ends of the groove 21 from each other along the circumferential direction. The groove 21 is a non-closed annular structure. If the groove 21 is a continuous annular structure, even with the protrusions, special tools (such as arc-shaped or segmented tools) can still disassemble it by bypassing the protrusions or by applying force from both sides of the groove 21. At the same time, the presence of the neck 23 enhances the strength of the central island 22, making it difficult to destroy or remove the central island 22.

[0036] Furthermore, the number of groove necks 23 can be set to one or more. When there are multiple groove necks 23, the multiple groove necks 23 divide the groove 21 into multiple independent segments. The length of each segment is greatly shortened, and the tool cannot apply force on the continuous groove 21. It is necessary to match the shape and position of all the segmented segments at the same time in order to rotate the screw, which greatly increases the difficulty of tool adaptation. Even if a special tool tries to embed into a certain segment of the groove 21, the presence of the groove neck 23 will block the possibility of it extending to adjacent segments or using force, completely eliminating the disassembly path of "bypassing the first protrusion 211".

[0037] The groove neck 23, together with the first protrusion 211 and the tapered surface, form a "triple anti-disassembly mechanism": the groove 21 and the first protrusion 211 limit the width of the tool → the tapered surface blocks the clamping of the tool → the groove neck 23 divides the groove 21 to block special tools. Under multiple protections, the reliability of anti-disassembly is greatly improved.

[0038] In some embodiments of this application, the angle between the outer circumferential surface of the screw head 2 and the end face of the screw head 2 away from the screw rod 1 is α, 45° < α < 75°. This tapering angle of 45° < α < 75° ensures that the inclination of the circumferential surface is sufficiently large (much greater than the 0° of a flat head), preventing common clamping tools (such as wrenches and pliers) from stably clamping the outer surface of the screw head 2 and completely blocking the clamping and disassembly path. Simultaneously, this angle range avoids insufficient end strength due to excessive steepness (α close to 0°), ensuring that the screw head 2 is not easily deformed or broken during tightening, disassembly, or under external force, thus balancing anti-tampering performance and durability. The anti-tamper screw of this application, through its tapering angle design of the screw head 2 (45° < α < 75°), solves the problems of contradiction between anti-tampering performance and structural strength, and incomplete tool compatibility blocking in related technologies. It achieves a balanced optimization of anti-tampering performance, structural durability, and processing feasibility, making it suitable for high-security scenarios.

[0039] In some embodiments of this application, at least one of the inner and outer sidewalls of the groove 21 is inclined, and the included angle between the inner and outer sidewalls is β, where β > 5°. If the sidewall of the groove 21 is vertical (β = 0°), tools (such as screwdrivers or special pry tools) can apply force stably by contacting the sidewall in parallel. Even if there is a protrusion or groove neck 23, disassembly can still be achieved by adjusting the angle or local prying. The vertical sidewall is prone to stress concentration when subjected to disassembly force, which can cause deformation or cracking of the edge of the groove 21, reducing the reusability or durability of the screw. The inclined sidewall prevents the tool from applying force stably through parallel contact. It must be perfectly matched with the inclination angle to be inserted into the groove 21. Otherwise, the tool will slip or the direction of force will be deviated due to the inclination of the sidewall, completely blocking the disassembly path of "partial prying" or "asymmetric force application". The design with an included angle β>5°, such as β=10° or 15°, further reduces the effective contact area between the tool and the sidewall. Even if a special tool tries to insert, it will not be able to transmit enough torque due to the small contact area, thus achieving dual anti-disassembly of "anti-insertion + anti-force application".

[0040] The sloping sidewalls disperse stress concentration during disassembly, avoiding edge deformation or cracking problems that are prone to occur with vertical sidewalls, and improving the durability of screws under repeated tightening, disassembly, or external force. The sloping sidewalls require tools to simultaneously match the sloping angle of the groove 21, the position of the protrusion, and the division of the neck 23. Any mismatch will lead to disassembly failure, achieving a high level of anti-theft with "one screw, one tool". General-purpose tools (such as screwdrivers and wrenches) cannot be matched with the sloping sidewalls, making disassembly completely impossible. Specialized tools also need to be designed individually for each screw, which is extremely costly.

[0041] In some embodiments of this application, the width of the groove opening of the groove 21 is L, and the width of the groove bottom of the groove 21 is M, where LM ≥ 0.5 mm. If the widths of the groove opening and the groove bottom of the groove 21 are close (LM is too small), the tool can penetrate deep into the bottom of the groove 21 and transmit torque through the sidewall contact. Even with the first protrusion 211 or the inclined sidewall, disassembly can still be achieved by adjusting the angle of force application. Relying solely on the sidewall shape and the groove neck 23 for separation, without further limiting the tool contact range through the width difference between the groove opening and the groove bottom, the anti-disassembly mechanism is simplistic and easily breached by targeted tools. If the groove bottom is too wide (LM is too small), stress may concentrate at the edge of the groove bottom during disassembly, causing deformation or breakage and reducing screw durability. If the width difference between the groove opening and the groove bottom is too small, processing errors (such as burrs or deformation) may easily cause the actual width difference to be lower than the design value, weakening the anti-disassembly effect.

[0042] The design with LM≥0.5mm makes the groove bottom width (M) significantly smaller than the groove opening width (L). The tool must simultaneously match the width of the groove opening and the narrow space at the bottom to be inserted and apply force. If the tool head width is greater than M, it cannot contact the side wall of the groove bottom, completely blocking the path of torque transmission through the groove bottom. Even if a specially designed tool attempts to insert from the groove opening, the tool head will slip out because the groove bottom is too narrow and cannot fully fit the side wall, achieving dual anti-embedding protection: "anti-insertion + anti-force application".

[0043] The disassembly tool must simultaneously meet multiple conditions, including the slot width (L), slot bottom width (M), side wall tilt angle (β), and 23-segment neck division, to disassemble the screw. Any mismatch will result in failure, achieving a high level of anti-theft with "one tool per screw." General-purpose tools (such as screwdrivers and wrenches) cannot fit the narrow space at the bottom of the slot, making disassembly impossible. Specialized tools also need to be designed individually for each screw, which is extremely costly.

[0044] In some embodiments of this application, the groove 21 is C-shaped. The C-shaped groove 21 is a non-closed structure (with gaps at both ends), and the tool must perfectly match the opening position, curvature, and gap width of the C-shape to be embedded. If the shape of the tool head does not match the C-shape (e.g., straight or polygonal), it will slip out because it cannot fit the contour of the groove 21, completely blocking the disassembly path of "partial embedding" or "asymmetric force application"; the opening design (gap) of the C-shape further limits the force application range of the tool. The tool must simultaneously cover the arc segment of the C-shape and the opening gap to transmit torque. Any mismatch will lead to disassembly failure, achieving dual anti-embedding and anti-force application.

[0045] In some embodiments of this application, the height of the first protrusion 211 protruding into the groove 21 is H, where H > L / 3. That is, the width of the groove 21 at the first protrusion 211 is at least 1 / 3 smaller than the width at other locations. This ensures that a tool that cannot be ground with a uniform thickness of sheet metal or tubing and then inserted into the groove 21 to unscrew the tamper-evident screw is securely fastened. The protrusion height of H > L / 3 creates a significant physical barrier; the tool must completely cross the protrusion to embed itself into the groove 21 and apply force. If the tool head is not thick enough or has insufficient elasticity, it will slip out due to the inability to pass through the protrusion, completely blocking the disassembly path of "bypassing the protrusion" or "partial embedding."

[0046] It should be noted that the groove 21 is connected to both sides of the first protrusion 211. That is, the first protrusion 211 does not cut off the groove 21, but rather narrows the width of the groove 21. For example, when the first protrusion 211 is formed on the outer side wall of the groove 21, a gap is formed between the top of the first protrusion 211 and the inner side wall of the groove 21.

[0047] In some embodiments of this application, there are multiple first protrusions 211, which are spaced apart circumferentially along the groove 21. The multiple first protrusions 211 distributed circumferentially form multiple physical barriers. The tool must simultaneously match the position, height (H>L / 3), and spacing of all the first protrusions 211 to be inserted into the groove 21. If the tool head cannot completely traverse all the protrusions, it will slip due to partial obstruction, completely blocking the disassembly path of "bypassing the protrusions" or "utilizing the anti-disassembly blind spot."

[0048] For example, in some embodiments of this application, the number of first protrusions 211 is two; of course, it can also be one, three, four, or more. The number and location of the first protrusions 211 are related to the size of the screw head and the size of the groove 21.

[0049] In some embodiments of this application, the screw head 2 includes a first connecting segment 202 and a second connecting segment 201, wherein the circumferential surface of the first connecting segment 202 is a cylindrical surface and the circumferential surface of the second connecting segment 201 is a gradually contracting conical surface.

[0050] The cylindrical surface of the first connecting section 202 provides a stable machining reference, allowing for dimensional control through high-precision turning or grinding. This ensures the machining accuracy of anti-disassembly structures such as the groove 21 and protrusions, preventing anti-disassembly failure due to taper errors. The conical surface of the second connecting section 201 retains anti-disassembly functionality (such as blocking clamping tools), while its segmented design reduces overall machining difficulty and improves consistency in mass production. The cylindrical first connecting section 202 can stably cooperate with standardized installation tools (such as positioning fixtures and automated assembly equipment), improving assembly efficiency and positioning accuracy. It is suitable for automated production lines or high-precision scenarios (such as electronic equipment and automotive parts). The gradually tapering second connecting section 201 retains anti-clamping functionality (such as α-angle design), ensuring positioning can be completed without special tools during installation, while preventing unauthorized disassembly.

[0051] The anti-tamper screw provided in this application embodiment solves the problems of contradiction between processing accuracy and anti-tamper performance, uneven structural stress distribution and insufficient installation adaptability in the prior art by using a two-segment design of the screw head (cylindrical surface + tapered shape). The technical effect is to achieve a balanced optimization of processing stability, structural durability and installation efficiency, and it is suitable for high-precision assembly and high-safety demand scenarios.

[0052] Furthermore, the axial height D of the first connecting segment 202 is less than 1mm. If the axial height of the first connecting segment 202 (cylindrical surface) is too large, tools (such as wrenches or pliers) may be able to disassemble by clamping the cylindrical surface, weakening the anti-clamping effect of the tapered second connecting segment 201. The cylindrical segment with a height of <1mm is extremely short, making it impossible for tools to stably clamp this segment and apply torque, completely blocking the path of "disassembly using the cylindrical segment". Because the cylindrical segment is too short, the tapered second connecting segment 201 is directly exposed, allowing its anti-clamping function to be fully utilized, achieving a dual anti-disassembly effect of "short reference + long tapered".

[0053] The anti-disassembly screw provided in this application solves the problems of tool clamping risk, insufficient redundancy of anti-disassembly mechanism, structural stress concentration and processing cost contradiction in the prior art by limiting the axial height of the first connecting section 202 (less than 1mm). The technical effect is to realize the superposition of "nine-fold anti-disassembly system", which significantly improves anti-clamping performance, structural reliability and processing economy.

[0054] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0055] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tamper-proof screw, characterized in that, include: Screw rod (1), A screw head (2) is provided at one end of the screw rod (1), and a central island platform (22) and a groove (21) are provided around the central island platform (22) on the end face of the screw head (2) away from the screw rod (1). A first protrusion (211) is provided on at least one side wall of the groove (21) so that the width of the groove (21) at the first protrusion (211) is reduced. The screw head (2) is at least partially set as a tapered cone in the direction away from the screw rod (1).

2. The tamper-proof screw according to claim 1, characterized in that, A neck (23) is formed between the two ends of the groove (21) in the circumferential direction, and the neck (23) isolates the two ends of the groove (21) from each other in the circumferential direction.

3. The tamper-proof screw according to claim 1, characterized in that, The angle between the outer circumferential surface of the screw head (2) and the end face of the screw head (2) away from the screw rod (1) is α, where 45° < α < 75°.

4. The tamper-proof screw according to claim 1, characterized in that, At least one of the inner and outer walls of the groove (21) is inclined, and the included angle between the inner and outer walls is β, where β > 5°.

5. The tamper-proof screw according to claim 4, characterized in that, The width of the groove opening of the groove (21) is L, and the width of the bottom of the groove (21) is M, where LM ≥ 0.5 mm.

6. The tamper-proof screw according to claim 1, characterized in that, The groove (21) is C-shaped.

7. The tamper-proof screw according to claim 4, characterized in that, The height of the first protrusion (211) protruding into the groove (21) is H, where H>L / 3.

8. The tamper-proof screw according to claim 1, characterized in that, The number of the first protrusions (211) is multiple, and the multiple first protrusions (211) are arranged at circumferential intervals along the groove (21).

9. The tamper-proof screw according to claim 1, characterized in that, The screw head (2) includes a first connecting section (202) and a second connecting section (201). The circumferential surface of the first connecting section (202) is a cylindrical surface, and the circumferential surface of the second connecting section (201) is a gradually contracting conical surface.

10. The tamper-proof screw according to claim 9, characterized in that, The first connecting segment (202) has an axial height of less than 1 mm.

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