A self-tapping, self-threading replaceable fastener

Abstract

The utility model discloses a kind of self-extruding hole self-tapping replaceable fastening screw, including screw head and screw rod part, screw rod part is successively divided into extruding hole part, reaming part, tapping part and fastening connecting part along the direction of screwing, extruding hole part is used to extrude screw hole on connected member, reaming part is used to enlarge the aperture of screw hole, tapping part is used to tap screw hole, and fastening connecting part is used to fasten connected member.The product realizes extruding hole, reaming, tapping, chip removal, tightening and sealing to complete once, and achieves the effect of fastening connection and sealing.

Description

Technical Field

[0001] This utility model belongs to the field of fasteners, and in particular to a fastening screw with replaceable self-tapping screw and self-extruding hole. Background Technology

[0002] Threaded fasteners, due to their simple structure, stability, reliability, and ease of replacement, are widely used in industries such as aircraft, automobiles, home appliances, construction, and energy storage. The typical assembly process involves: determining the installation position and marking the location of two (or more) connected parts, then drilling, chip removal, tapping, chamfering, tightening bolts, and finally applying sealant (if a specific sealing requirement exists). This process involves numerous processing steps, tools, and equipment, resulting in cumbersome installation, long processing times, and high costs. Currently, industries like automobiles and home appliances are pursuing efficiency, automation, and unmanned operation. From a functional perspective, the pre-processing steps of marking, drilling, chip removal, tapping, and chamfering contribute no value. Therefore, using a screw that allows for direct assembly without pre-processing, replacing the complex installation method, is a highly valuable and technically challenging solution. Utility Model Content

[0003] This invention proposes a replaceable fastening screw with a self-extruding hole and a self-tapping screw, aiming to solve the technical problem that the connected parts need to be pre-processed due to the existing screw structure.

[0004] To solve the above-mentioned technical problems, the technical solution of this utility model is: a self-expanding hole self-tapping replaceable fastening screw, including a screw head and a screw shank, characterized in that: the screw shank is divided into an extrusion hole part, an expansion hole part, a tapping part and a fastening connection part along the screwing direction, the extrusion hole part is used to extrude a screw hole on the connected parts, the expansion hole part is used to enlarge the diameter of the screw hole, the tapping part is used to tap the screw hole, and the fastening connection part is used to fasten the connected parts.

[0005] Further defining the above technical solution, the extrusion hole is triangular in shape, the cross-sectional shape of the triangular tail tip is an irregular circular structure composed of multiple arc edges, and the outer diameter of the triangular tail tip gradually decreases from the head to the tail.

[0006] To further define the above technical solution, the enlarged hole portion is a triangular pyramid, and the cross-sectional shape of the triangular pyramid is an irregular circular surface structure composed of multiple arc edges.

[0007] Further defining the above technical solution, the cross-sectional shape of the tapping part is an irregular circular structure composed of multiple arc edges, and the outer surface of the tapping part is provided with tapping threads.

[0008] To further define the above technical solution, the structure of the fastening connection includes a cylinder with fastening threads on its outer surface.

[0009] A further improvement to the above technical solution is that a locking disc is provided at the connection between the screw head and the screw shank, which is integrally formed with the screw head. An arc groove is recessed on the end face of the locking disc with the screw shank as the center of the groove.

[0010] Beneficial Effects: Based on the principle of metal plastic forming, this product combines a unique external structure with mechanical properties. During installation, the unique tail section first extrudes a hole in the connected parts. Once the hole diameter reaches a certain size, the screw's special cross-sectional shape expands the hole. Then, under the action of the screw's special thread, the hole is tapped. Finally, the screw's body thread tightly engages with the hole thread, forming a bearing surface and a gapless sealing surface. This achieves extrusion, reaming, tapping, chip removal, tightening, and sealing in one step, achieving a fastening connection and sealing effect. This product is over 90% more efficient and over 80% cheaper than traditional installation methods. Due to its standardized structure, it can be automatically and continuously installed by robots, making it particularly suitable for mass production on production lines. Attached Figure Description

[0011] Figure 1 This utility model is a three-dimensional Figure 1 .

[0012] Figure 2 This utility model is a three-dimensional Figure 2 .

[0013] Figure 3 This is a cross-sectional view of the extrusion hole.

[0014] Figure 4 This is a cross-sectional view of the tapping section.

[0015] Figure 5 This is a cross-sectional view of the fastening connection.

[0016] Figure 6 It is a cross-sectional view of the actual object. Detailed Implementation

[0017] like Figure 1 and Figure 2 As shown, a replaceable self-expanding self-tapping fastening screw includes a screw head 1 and a screw shank, which are integrally formed. The screw shank is divided into an extrusion hole 2, an enlargement hole 3, a tapping hole 4, and a fastening connection 5 along the screwing direction. The extrusion hole is used to extrude a screw hole on the connected parts, the enlargement hole is used to enlarge the diameter of the screw hole, the tapping hole is used to tap the screw hole, and the fastening connection is used to fasten the connected parts.

[0018] like Figure 3As shown, the extrusion section 2 is triangular with a pointed tip. The cross-sectional shape of the triangular tip is an irregular circular surface 201 structure composed of multiple rounded edges. The outer diameter of the triangular tip gradually decreases from the head to the tail. The triangular tip is similar to a cone, with three smooth edges protruding outwards from the cone surface. When the screw contacts the metal being connected, the screw applies great pressure to the contact surface while rotating at high speed, putting the contact surface in a state of triaxial compressive stress. Due to the principle of least resistance, the metal being connected flows plastically in the direction of least resistance, without cutting motion (i.e., tearing of the base material), thus ensuring that defects such as micro-cracks are not generated. The tail of the triangular tip is selected as a blunt tip or a large rounded triangular pyramid tip, with smooth transitions at the segmentation points to avoid stress concentration during processing.

[0019] The enlarging section 3 is a triangular pyramid, and the cross-sectional shape of the pyramid is an irregular circular structure composed of multiple arc edges. To quickly enlarge the hole cross-section to the thread root diameter, the screw has a section shaped like a regular triangular pyramid to minimize enlarging resistance, allow for plastic flow of the metal inside the hole, and prevent chip generation. The cross-sectional shape of the enlarging section can be referenced from the cross-sectional diagram of the tapping section.

[0020] like Figure 4 As shown, the cross-sectional shape of the tapping part 4 is an irregular circular surface 401 structure composed of multiple arc edges, and the outer surface of the tapping part is provided with tapping threads 402. The tapping part utilizes the tapping principle of extrusion taps, and designs a tapping thread between the enlarged hole of the screw and the normal thread to achieve the formation of an effective thread in the enlarged hole.

[0021] like Figure 5 As shown, the structure of the fastening connection part 5 includes a cylinder 501, and a fastening thread 502 is provided on the outer surface of the cylinder; the same as the fastening thread of a conventional screw.

[0022] like Figure 1 As shown, a locking disc 6 is integrally formed with the screw head at the connection between the screw head and the screw shank. An arc groove 601 is recessed on the end face of the locking disc with the screw shank as the center of the groove. Utilizing the principles of metal springback and plastic flow, a gapless interference fit is achieved, and the screw support surface and the connected body are seamlessly filled, providing a sealing effect without the need for sealant.

[0023] The screw head has no chamfer and adopts a straight edge structure. Because the screw head protrudes from the surface of the connector, in order to avoid interference and improve the appearance, the head height is minimized. Therefore, the top and sides of the screw head are not chamfered or beveled, and straight edges are used to maximize the contact area between the head and the tightening tool and prevent slippage.

[0024] In order for the bolt to exert greater pressure on the material it is connecting as soon as it makes contact, the screw surface must have high hardness. However, the screw must maintain a certain degree of rigidity and elasticity when the hole is enlarged and tapped. Therefore, the screw is surface carburized.

[0025] Normally, threaded connections require drilling, tapping, screwing in screws, and applying adhesive, each step requiring specialized equipment, tools, fixtures, and inspection or measurement. This product offers multiple functions including hole extrusion, hole enlargement, tapping, fastening, and sealing. It can be installed directly without precise positioning, pre-drilled holes, pre-tapping internal threads, or pre-applying adhesive.

[0026] The locking disc on the screw makes tight contact with the connected body, forming a dry seal, which has high water tightness and air tightness. For example... Figure 6 As shown, the connected body includes an upper plate 7 and a lower plate 8. When the screw is screwed into the connected body, the hole diameter is smaller than the screw's outer diameter. Utilizing the principle of extrusion tapping, when the screw is screwed in, the metal of the hole wall undergoes plastic deformation (the screw is harder than the connected body). After installation, due to the metal springback, the threaded hole and the screw form an interference fit, achieving a seamless connection. According to the extrusion tapping principle, during the plastic flow of metal, a portion of material will inevitably protrude from the workpiece surface (generally called a flange). An appropriately sized arc groove can accommodate this excess flange material and form a stable compressive stress ring, improving the material's sealing performance.

[0027] When the connected parts need to be disassembled (such as for maintenance or material replacement), or when the screw is abnormally damaged, this product can be unscrewed with an Allen wrench (the same as for common screws), and replaced with a new screw (if the original screw is not damaged, it can continue to be used). Then, screw it in normally. If sealing is required, the screw needs to be coated with sealant.

[0028] This utility model belongs to the field of metal sheet connection and can be widely used in industries such as automobiles, energy storage, home appliances, and packaging. It can replace ordinary connection methods such as bolts, screws, welding, riveting, and adhesive.

Claims

1. A self-tapping, self-threading replaceable fastener screw comprising a screw head portion and a screw shank portion, characterized by: The screw shank is divided into a hole-forming section, a hole-expanding section, a tapping section, and a fastening connection section along the screw-in direction. The hole-forming section is used to extrude a screw hole on the connected parts, the hole-expanding section is used to enlarge the diameter of the screw hole, the tapping section is used to tap the screw hole, and the fastening connection section is used to fasten the connected parts.

2. The self-tapping replaceable fastening screw of claim 1, wherein: The extrusion hole is triangular in shape with a pointed tip. The cross-sectional shape of the triangular tip is an irregular circular structure composed of multiple arc edges. The outer diameter of the triangular tip gradually decreases from the head to the tail.

3. The self-tapping replaceable fastener screw of claim 1 or 2, wherein: The enlarged hole is a triangular pyramid, and the cross-sectional shape of the triangular pyramid is an irregular circular structure composed of multiple arc edges.

4. The self-tapping replaceable fastening screw of claim 3, wherein: The cross-sectional shape of the tapping part is an irregular circular structure composed of multiple arc edges, and the outer surface of the tapping part is provided with tapping threads.

5. The replaceable self-tapping screw with a self-expanding hole as described in claim 1, characterized in that: The connection between the screw head and the screw shank is provided with a locking disc integrally formed with the screw head. The end face of the locking disc has an arc groove recessed inward with the screw shank as the center of the groove.

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