High-toughness weather-resistant flow-drilling screw

Abstract

The utility model discloses a kind of high tough weather-resistant flow drill screws, including head, stem and tip. The head has driving structure, and the stem includes connecting section, threaded section and light pole section in order from the head towards the tip direction. The core improvement of the present application is that: the cross section of the tip is circular arc triangle and continuously decreases along the direction towards the tip tip, and the included angle α between the side surface of the tip and screw axis is 10°~40°. Compared with prior art, the specific included angle α range can make screw tip when attacking into material, reach the best balance between sharpness and guiding stability. It ensures enough sharpness to reduce initial drilling resistance, so as to significantly improve the drilling efficiency of screw, drilling accuracy and the forming quality of final thread.

Description

Technical Field

[0001] This utility model belongs to the field of flow drill screw technology, specifically relating to a high-strength, tough, and weather-resistant flow drill screw. Background Technology

[0002] Flow drill screws, as a highly efficient self-drilling fastener, are widely used in thin-plate connections in automotive manufacturing, aerospace, home appliances, and building steel structures. These applications often face complex service environments, placing stringent requirements on fasteners for high strength, toughness, and weather resistance. Their greatest advantage lies in their ability to drill a hole in the material being joined using the tip during the screwing process, followed by direct extrusion through the threaded section to form an internal thread. This allows drilling, tapping, and fastening to be completed in a single step, eliminating the need for pre-drilling and tapping, significantly improving assembly efficiency.

[0003] However, despite the aforementioned advantages of existing flowing drill screws, their overall performance still suffers from several shortcomings that require further optimization in practical applications. For example, the tip angle design of existing flowing drill screws often fails to achieve an optimal balance between drilling resistance and guiding stability. An angle that is too small may result in an overly sharp tip with insufficient strength, making it prone to breakage or severe wear when encountering hard materials or impurities. Conversely, an angle that is too large leads to a significant increase in axial penetration force and a decrease in tip centering ability, causing the screw to easily "drift" or "slip" during the drilling initiation phase. This not only affects drilling position accuracy but also results in incomplete thread formation and reduced connection strength. These problems directly restrict the full realization of the high strength, toughness, and weather resistance of flowing drill screws.

[0004] In summary, there is an urgent need in this field for a new type of flow drill screw that can ensure excellent drilling guidance and low penetration resistance while also possessing high strength, toughness, and weather resistance. Utility Model Content

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution.

[0006] A high-strength, tough, and weather-resistant flow drill screw includes a head, a shank, and a tip. The head has a drive structure. The shank, from the head towards the tip, sequentially includes a connecting section, a threaded section, and a smooth section. The tip has a cross-section that is an arcuate triangle that continuously decreases in the direction towards the tip tip. The angle α between the side of the tip and the screw axis is 10° to 22°. This angle range ensures that the tip has sufficient sharpness to reduce initial resistance when penetrating the material.

[0007] In a preferred embodiment of a high-strength, tough, weather-resistant flow drill screw, the included angle α is 20°~22°. This angle can minimize axial penetration force, reduce energy loss, and ensure extremely high drilling accuracy and thread forming quality, effectively preventing the risk of material cracking or thread stripping.

[0008] As a preferred embodiment of a high-strength, tough, and weather-resistant flow drill screw, the threaded section comprises a fastening section and a forming section sequentially from the head towards the tip. The maximum outer diameter of the forming section gradually decreases along its length from the end near the fastening section towards the end of the smooth section. This forming section smoothly compresses the material during tapping, gradually forming a complete thread profile, significantly reducing the tightening torque and internal material stress, and effectively preventing material cracking or thread irregularities caused by stress concentration.

[0009] As a preferred embodiment of a high-strength, tough, and weather-resistant flow drill screw, the smooth section has a circular arc triangular cross-section. This creates multiple line contact points between the screw and the workpiece hole wall after screw insertion. This unique cross-sectional shape helps to break up and guide debris generated from the tip during screw insertion, reducing the risk of chip clogging, and is particularly suitable for machining tough materials.

[0010] In a preferred embodiment of a high-strength, tough, weather-resistant flow drill screw, the connection between the connecting section and the head is provided with a recessed groove extending inward toward the head. This groove provides additional space for chip removal and discharge from the tip. Furthermore, the recessed groove structure makes the end of the connecting section more susceptible to plastic deformation under pressure and outward curling, forming a robust rivet joint, thus improving connection reliability. In assembly with a counterpart (such as the plate being connected), this groove acts as a clear limiting and tolerance-absorbing structure. It ensures that the screw head achieves surface contact and stable fit with the counterpart surface during tightening, improving the rigidity and stability of the connection.

[0011] As a preferred embodiment of a high-strength, tough, and weather-resistant flow drill screw, the outer diameter of the connecting section gradually decreases from the shank towards the head. The tapered design of the connecting section, combined with the groove design, allows the material to flow more smoothly towards the head and bevel, forming a well-shaped, high-strength rivet head.

[0012] In a preferred embodiment of a high-strength, tough, and weather-resistant flow drill screw, the groove has a first groove wall and a second groove wall. The first groove wall is parallel to the screw's axis and connects to the connecting section. The second groove wall has an angle with the screw's axis, making the groove flared. The first and second groove walls are rounded. The flared structure formed by the angled second groove wall provides a smoother channel for debris to be discharged upwards and optimizes the deformation space for the plastic flow of material during riveting. The first groove wall, parallel to the axis, can serve as an axial positioning reference, ensuring precise positioning during assembly.

[0013] Compared with the prior art, this application has the following beneficial technical effects: the angle range allows the tip to have sufficient sharpness when penetrating the material to reduce the initial resistance, achieve a balance between drilling resistance and guiding stability, and improve the drilling efficiency and thread forming quality of the screw. Attached Figure Description

[0014] Figure 1 This is a side view of the head of the flow drill screw.

[0015] Figure 2 for Figure 1 Sectional view at point AA.

[0016] Figure 3 for Figure 2 Sectional view at point BB.

[0017] Figure 4 for Figure 2 A magnified view of a section at point C.

[0018] Figure 5 For comparison, a test data table is provided.

[0019] The following is an explanation of the reference numerals in the attached figures:

[0020] 1. Head; 2. Connecting section; 3. Fastening section; 4. Forming section; 5. Smooth rod section; 6. Tip; 7. Groove; 8. First groove wall; 9. Second groove wall. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] In the following embodiments, the same or similar reference numerals denote the same or similar components or components with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this utility model, it should be understood that the terms such as center, longitudinal, transverse, length, width, thickness, upper, lower, front, back, left, right, vertical, horizontal, top, bottom, inner, outer, clockwise, and counterclockwise, indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description; therefore, they should not be construed as limitations on this utility model. 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 technical features shown. In the description of this utility model, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," etc., should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0024] Reference Figures 1 to 4 A high-strength, tough, and weather-resistant flow drill screw includes a head 1, a shank, and a tip 6. The head 1 has a drive structure that can be used with a standard electric screwdriver bit. The shank, from the head 1 toward the tip 6, includes a connecting section 2, a threaded section, and a smooth section 5. The smooth section 5 has a circular arc triangular cross-section, which forms three continuous line contacts with the workpiece hole wall after screwing in. This not only serves as centering but also promptly breaks up and guides the metal chips generated at the tip 6 upwards, significantly reducing the risk of chip clogging common in tough materials and making the tightening process smoother.

[0025] The cross-section of tip 6 is an arcuate triangle that continuously decreases in the direction toward the tip of tip 6. The angle α between its side and the screw axis (see...) Figure 2 The angle is defined as the angle between the tangent of the outer contour of the side surface at the midpoint of the axial direction of the tip and the axis, ranging from 10° to 22°. To verify this rule, a comparative test was conducted on a double-layer plate composed of 0.8mm steel plate and 2.0mm aluminum plate (see...). Figure 5 When using a screw with an α of 10°, the peak penetration torque is 1.9 N·m, the hot-melt time is as long as 0.32 s, the bottom burr is as high as 0.18 mm, and the breaking tensile force is 2.9 kN. When using a screw with an α of 20°, the penetration torque increases to 2.6 N·m, the hot-melt time is shortened to 0.23 s, the burr height is reduced to 0.07 mm, and the breaking tensile force increases to 3.5 kN. When using a screw with an α of 22°, the peak torque is 2.8 N·m, the hot-melt time is shortened to 0.21 s, the burr is only 0.06 mm, and the breaking tensile force reaches 3.6 kN. When using a screw with an α of 40°, the penetration torque increases to 4.1 N·m, the hot-melt time is shortened to 0.15 s, the burr is only 0.04 mm, and the breaking tensile force reaches 3.4 kN. Although the hot-melt time is the shortest and the burr is the fewest, the screw breakage rate increases to 7%, and the final tightening torque also exceeds the setting range of conventional tools. Experiments show that if α is too small, the cutting ability is insufficient and the hot melt time is prolonged; if α is too large, the axial resistance increases sharply, and torque overload or even screw breakage is likely to occur.

[0026] Furthermore, α is determined to be the preferred angle range of the present invention, which can achieve the best balance between penetration power, joint strength and appearance quality.

[0027] In this application, the threaded section, from the head 1 towards the tip 6, sequentially includes a fastening section 3 and a forming section 4. The maximum outer diameter of the forming section 4 gradually decreases from the end near the fastening section 3 towards the end of the smooth section 5. During tapping, the material can be gradually squeezed, reducing the instantaneous torque peak and preventing microcracks or thread irregularities in the aluminum alloy due to stress concentration. A recessed groove 7 is provided at the connection point between the connecting section 2 and the head 1, extending inward towards the head 1. The groove 7 provides additional space for chip removal and discharge from the tip 6. Furthermore, the recessed groove 7 structure makes it easier for the end of the connecting section 2 to undergo plastic deformation under pressure and roll outward, forming a strong rivet joint, improving connection reliability. In assembly with a counterpart (such as a connected plate), the groove 7 can serve as a clear limiting and tolerance-absorbing structure. It ensures that the screw head 1 achieves surface contact and stable fit with the counterpart surface during tightening, improving the rigidity and stability of the connection.

[0028] The outer diameter of the connecting section 2 gradually decreases from the shank towards the head 1. The tapered design of the connecting section 2, combined with the groove 7, allows the material to flow more smoothly towards the head 1 and bevel, forming a regular-shaped, high-strength rivet head. The groove 7 has a first groove wall 8 and a second groove wall 9. The first groove wall 8 is parallel to the axis of the screw and connects to the connecting section 2. The second groove wall 9 has an angle with the axis of the screw, making the groove 7 flared. The first groove wall 8 and the second groove wall 9 are rounded. The flared structure formed by the angled second groove wall 9 provides a smoother channel for debris to be discharged upwards and provides optimized deformation space for the plastic flow of material during riveting. The first groove wall 8, parallel to the axis, can serve as an axial positioning reference to ensure precise positioning during assembly.

[0029] The scope of protection of this utility model includes, but is not limited to, the above embodiments. The scope of protection of this utility model is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art shall fall within the scope of protection of this utility model.

Claims

1. A high-strength, tough, weather-resistant flow drill screw, comprising a head (1), a shank, and a tip (6), wherein the head (1) has a drive structure, the shank comprises, from the head (1) toward the tip (6), a connecting section (2), a threaded section, and a smooth shank section (5), and the tip (6) has a cross-section in the shape of an arcuate triangle that continuously decreases in the direction toward the tip (6), characterized in that, The included angle α between the side of the tip (6) and the screw axis is 10°~22°.

2. The high-strength, tough, weather-resistant flow drill screw according to claim 1, characterized in that, The included angle α is 20°~22°.

3. The high-strength, tough, weather-resistant flow drill screw according to claim 1, characterized in that, The threaded section includes a fastening section (3) and a forming section (4) in sequence from the head (1) toward the tip (6). The maximum outer diameter of the forming section (4) gradually decreases along itself from the end near the fastening section (3) toward the end of the smooth rod section (5).

4. The high-strength, tough, weather-resistant flow drill screw according to claim 1, characterized in that, The cross-section of the bare rod segment (5) is a circular arc triangle.

5. A high-strength, tough, weather-resistant flow drill screw according to claim 1, characterized in that, The connection between the connecting segment (2) and the head (1) is provided with a groove (7) that is recessed inward toward the head (1).

6. A high-strength, tough, weather-resistant flow drill screw according to claim 5, characterized in that, The outer diameter of the connecting section (2) gradually decreases in the direction from the rod towards the head (1).

7. A high-strength, tough, weather-resistant flow drill screw according to claim 6, characterized in that, The groove (7) has a first groove wall (8) and a second groove wall (9). The first groove wall (8) is parallel to the axis of the screw and connected to the connecting section (2). The second groove wall (9) has an angle with the axis of the screw so that the groove (7) is flared. The first groove wall (8) and the second groove wall (9) are rounded.

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