Anti-loose cross slot screw

Abstract

The utility model discloses a kind of anti-disengagement cross slot screws, it is related to screw technical field.The screw includes screw head and cross slot, the central portion of cross slot bottom is equipped with boss, boss surface is provided with fluorescent layer or top is embedded with reflector;The load-bearing surface of the screw head, around the cross slot mouth, is provided with anti-slip tooth pattern slightly protruding on the load-bearing surface;The depth of the cross slot gradually increases from outside to inside.The utility model provides centering guide and radial limit by boss, provides auxiliary anti-slip resistance when screwdriver is slightly lifted by anti-slip tooth pattern, the synergistic effect of both, effectively solve the problem that traditional cross slot screw is easy to slip off, damage workpiece.Meanwhile, optical boss is convenient for quick alignment in dim environment, gradual change groove depth design makes torque transmission more stable, significantly improves installation precision, efficiency and reliability.

Description

Technical Field

[0001] This utility model relates to the field of screw technology, specifically to a cross-head screw with functions of preventing loosening, increasing torque, and facilitating alignment. Background Technology

[0002] Cross-head screws are widely used in various fields such as machinery manufacturing, electronic products, and furniture assembly due to their ease of use with tightening tools. However, existing cross-head screws have long faced some technical problems that urgently need to be solved in practical applications.

[0003] First and foremost, the most prominent problem is that screwdrivers (or bits) are extremely prone to slipping out of their slots. This is mainly due to the following reasons: 1) During tightening, especially when high torque is required or operating space is limited, it is difficult for the operator to maintain perfect coaxiality between the screwdriver and the screw. Even a slight angular deviation causes the screwdriver tip to generate an outward force under the inclined surface of the slot wall, causing it to jump out of the slot. 2) The bottom of the Phillips head slot is usually flat, and the tip of the screwdriver lacks an effective axial support point, making it highly susceptible to misalignment under lateral forces. This slippage not only scratches the workpiece surface, affecting the product's appearance, but also damages the screw's slot, making it impossible to tighten or remove again, causing significant difficulties for repair and assembly. For high-value or high-safety products (such as aerospace vehicles and precision instruments), damage caused by screw slippage can be catastrophic.

[0004] Secondly, the torque transmission performance of traditional Phillips head screws is not ideal. Because the groove depth is generally uniform, the contact area between the screwdriver tip and the groove wall is limited. Under high torque, the contact stress is highly concentrated, easily leading to groove wear or even "stripping." Once the groove is damaged, the torque transmission capacity drops sharply, greatly increasing the risk of screw failure. Furthermore, this unstable torque transmission makes it difficult to control installation accuracy, failing to meet the requirements of high-precision assembly.

[0005] Furthermore, in dimly lit, confined, or fast-alignment environments (such as internal equipment maintenance or nighttime outdoor work), operators find it difficult to quickly and accurately align and insert the screwdriver tip into the center of the Phillips head slot, reducing work efficiency and increasing operational difficulty.

[0006] To address the slippage problem, some attempts have been made in existing technologies, such as increasing the groove depth or changing the groove wall angle. However, these methods have limited effectiveness and may weaken the screw head strength. Other solutions involve complex locking mechanisms, but these are costly to manufacture and difficult to popularize. Therefore, there is an urgent need in the field for a Phillips head screw that is simple in structure, low in cost, effectively prevents screwdriver slippage, improves torque transmission efficiency, and facilitates alignment. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention aims to provide a cross-head screw that can effectively prevent loosening and has smooth torque transmission and fast alignment.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A type of anti-loosening Phillips head screw includes a screw head and a Phillips head groove formed therein. A boss is provided at the center of the bottom of the Phillips head groove. A fluorescent layer is provided on the surface of the boss groove or a reflective sheet is embedded on its top. Anti-slip teeth are provided on the bearing surface of the screw head groove, which are slightly raised above the bearing surface.

[0009] Preferably, the boss is a cylindrical frustum, a conical frustum, or a quadrangular pyramidal frustum.

[0010] Preferably, the bottom of the cross groove is filled with a filling material that contrasts sharply with the color of the screw body, forming a visual background that is distinct from the boss.

[0011] Preferably, the filler material is white or light-colored engineering plastic, and the screw body is made of dark metal.

[0012] Preferably, the boss is integrally formed with the bottom of the cross groove.

[0013] Preferably, the depth of the cross groove gradually increases from the outside to the inside.

[0014] Compared with the prior art, this utility model has the following advantages: 1. Anti-hair loss performance The physical limiting function of the boss: The boss provides a clear and solid "seat" for the tip of the screwdriver bit, preventing it from excessively squeezing the bottom material of the groove under excessive axial pressure, and ensuring that the side of the screwdriver bit and the gradient groove wall are in the optimal engagement position.

[0015] Centering guidance: The boss guides the screwdriver tip to the center, ensuring even contact between the four side wings and the groove wall. Slippage often occurs when the engagement is insufficient or the screwdriver is tilted. Therefore, a properly centered, deep, and sufficient engagement is inherently very difficult to dislodge.

[0016] In addition, the contact between the boss and the tip of the screwdriver forms an additional central force point, which, together with the four groove walls of the Phillips head, constitutes a "five-point positioning" stabilizing force system, greatly enhancing the stability of the screwdriver within the groove.

[0017] The anti-slip serrations provide double protection: the slightly raised anti-slip serrations surrounding the groove form a "second line of defense." Even if the screwdriver is slightly lifted in extreme situations, its sidewalls will engage and rub against the anti-slip serrations, providing additional resistance to slippage. This dual protection design of "central boss anti-slip + end face serration anti-slip" ensures extremely high operational reliability.

[0018] 2. Smooth torque transmission and high installation precision The gradually increasing depth design of the Phillips head groove, from the outside to the inside, increases the contact area between the screwdriver tip and the groove wall during screwing, resulting in more linear and stable torque transmission. This avoids the impact and stress concentration caused by sudden force in traditional constant-depth grooves, effectively reducing the risk of "stripping" the groove and extending the service life of screws and tools. At the same time, the stable torque transmission facilitates more precise tightening control.

[0019] 3. Excellent rapid alignment and observation capabilities Optical alignment guidance: The protrusion, made of fluorescent material or with a reflective plate embedded on top, forms a bright spot when illuminated. In dim environments or with poor visibility, this spot clearly marks the center position of the cross-shaped slot, guiding the operator to quickly and accurately align the screwdriver, greatly improving work efficiency and ease of operation.

[0020] Visual Inspection of Coating Quality: Furthermore, the bottom of the cross groove can be filled with a filler material that contrasts sharply with the color of the screw body (e.g., a white filler for a dark screw). This design results in a very high visual contrast in the groove depth. After surface treatment (e.g., electroplating, spraying), the operator can immediately determine whether the coating layer is too thick and has filled the bottom of the groove, thereby quickly screening out defective products and ensuring the assembly quality of the screws.

[0021] 4. Simple structure, high strength, and easy to manufacture. All improved features (boss, anti-slip teeth, and gradient groove depth) can be formed in one step or completed in subsequent processing using conventional screw machining processes such as cold heading and milling, without the need for complex procedures and with minimal cost increase. The boss structure is located in the center of the groove bottom, which not only does not weaken the head strength, but may even slightly enhance it due to its reinforcing effect. Attached Figure Description

[0022] Figure 1 Top view of the head of a Phillips head screw; Figure 2 This is a cross-sectional view of the screw head AA.

[0023] In the diagram: 1-Screw head; 2-Phillips head groove; 3-Boss; 4-Anti-slip teeth. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0025] like Figure 1 and Figure 2 As shown in the figure, this embodiment provides an anti-loosening Phillips head screw, which mainly includes a screw head 1 and a threaded shank (not fully shown in the figure). A standard Phillips head groove 2 is machined on the end face (i.e., the bearing surface) of the screw head 1.

[0026] The core improvement in this embodiment lies in the cross groove 2 and its surrounding structure, as detailed below: Boss 3: At the very center of the bottom of the cross groove 2, a frustum-shaped metal boss 3 is integrally formed using cold heading or milling processes. To achieve optical alignment, a fluorescent coating or tiny reflective sheet is attached to the surface of this metal boss 3 through coating, electroplating, or inlay processes. For example, a layer of durable fluorescent paint can be applied, or a miniature glass microbead reflective sheet can be inlaid. In dim lighting conditions, when illuminated by ambient light or a special flashlight, this boss 3 will emit a striking fluorescence or strong reflection, clearly marking the center position of the groove.

[0027] Anti-slip teeth 4: On the bearing surface of the screw head 1, three rings of discontinuous serrated anti-slip teeth 4 are machined around the groove of the cross groove 2, slightly raised above the bearing surface. The height of these teeth is very small, about 0.1 mm, so they will not hinder the normal insertion of the screwdriver.

[0028] Gradient groove depth: from Figure 2 The cross-sectional view clearly shows that the depth of the cross groove 2 is not constant, but rather gradually increases linearly from the groove opening to the bottom (i.e., towards the inside of the screw). This design ensures that after the screwdriver tip is fully inserted, the contact surface between its sidewall and the groove wall is a continuous slope, resulting in good contact.

[0029] Color Filling: In a preferred embodiment, the bottom of the cross groove 2 (i.e., the gradually deepening slope) is filled with white wear-resistant epoxy resin material (not shown separately in the figure), while the screw body is black alloy steel. This strong black and white contrast makes the groove depth very easy to observe.

[0030] Working Principle: When using the included screwdriver for tightening, the screwdriver tip is easily aligned with the center under the guidance of the fluorescent protrusion 3. After insertion, the screwdriver tip abuts against protrusion 3, obtaining axial support. When torque is applied, the torque is mainly transmitted through the close contact between the screwdriver sidewall and the groove wall of the gradually deepening groove, resulting in a smooth process. If vibration or tilting occurs during operation, causing the screwdriver to tend to lift upwards, its sidewall will immediately contact the anti-slip teeth 4, generating frictional resistance and preventing it from completely sliding out of the groove.

[0031] The mechanism of anti-slip teeth: ① Triggering condition: The screwdriver's "micro-lift". In actual operation, especially when applying large torque or when using power tools that generate vibration, the screwdriver cannot always maintain perfect insertion. It will experience slight, instantaneous "axial lift" and "tilt". Causes of lift include: Vibration: The vibration of the power tool will cause the screwdriver head to jump slightly off the bottom of the slot at a high frequency. Uneven force applied by the operator: When operating manually, the downward pressing force may decrease momentarily. Foreign objects in the slot: Fine metal shavings or dirt may be lodged at the bottom of the slot, preventing the screwdriver head from settling completely. ② Moment of action: The instant from "slot wall transmission" to "end face contact". When the screwdriver head undergoes a micro-lift, the engagement between its side wall and the side wall of the cross slot 2 becomes incomplete, resulting in a small gap. At this time, if the screwdriver is simultaneously subjected to a torsional force (torque), the lower edge of its side wall will scrape and contact the end face of the screw head 1, or is about to do so. It is at this critical moment that the anti-slip teeth begin to function. ③ Mechanism of Action: From "Sliding Friction" to "Meshing Resistance". If the end face is smooth: The lower edge of the screwdriver's sidewall contacts the smooth screw end face, resulting in pure sliding friction with minimal resistance. The screwdriver can easily slide completely out of the slot under torque. If there are anti-slip teeth: The lower edge of the screwdriver's sidewall will engage with or abut against the slightly raised anti-slip teeth. This instantaneous contact is no longer simple sliding, but produces a slight "meshing" or "ploughing" effect. To continue sliding, the screwdriver needs to overcome greater resistance, either "climbing" over the teeth or slightly "gnawing" at the top of the teeth. This instantaneous increase in resistance is sufficient for the operator to notice, or sufficient to counteract the slight lifting inertia, forcing the screwdriver tip to fall back into the cross-shaped groove under inertia, restoring effective engagement.

[0032] During production, quality inspectors only need to visually inspect the product. If the white bottom of the tank is clearly visible, the coating is considered qualified. If the bottom of the tank is covered with a black coating, it is considered a defective product, thus achieving rapid and non-destructive quality screening.

[0033] In summary, this utility model, through its ingenious structural combination, solves several long-standing technical problems, such as easy slippage of cross-head screws, unstable torque transmission, difficulty in alignment, and difficulty in inspecting coating quality. It has extremely high practical value and market prospects.

[0034] The above embodiments are merely preferred embodiments of this utility model and are not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A Phillips head screw with anti-loosening properties, comprising a screw head (1) and a Phillips head groove (2) formed in the screw head (1), characterized in that: The bottom center of the cross groove (2) is provided with a boss (3), the surface of the boss (3) is provided with a fluorescent layer or the top is embedded with a reflective sheet; the bearing surface of the screw head (1) is provided with anti-slip teeth (4) that are slightly raised above the bearing surface and surround the groove of the cross groove (2).

2. The anti-loosening cross-head screw according to claim 1, characterized in that: The boss (3) is a cylindrical frustum, a conical frustum, or a quadrangular pyramidal frustum.

3. The anti-loosening cross-head screw according to claim 1, characterized in that: The bottom of the cross groove (2) is filled with a filling material that contrasts sharply with the color of the screw body, forming a visual background that is distinct from the boss (3).

4. The anti-loosening cross-head screw according to claim 3, characterized in that: The filler material is white or light-colored engineering plastic, and the screw body is made of dark metal.

5. The anti-loosening cross-head screw according to claim 1, characterized in that: The boss (3) and the bottom of the cross groove (2) are integrally formed.

6. The anti-loosening cross-head screw according to claim 1, characterized in that: The depth of the cross groove (2) gradually increases from the outside to the inside.

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