A self-tapping fastener integrated with a machine thread

Abstract

The utility model relates to the technical field of fastener, especially to a fastener integrating self-tapping and machine thread, comprising a rod part, which is sequentially divided into a self-tapping section and a machine thread section from front to back; the rod part at the self-tapping section is triangular, and the rod part front end is provided with a triangular guide head; the thread cross section of the self-tapping section is triangular, used for self-tapping to form internal thread in a light hole, and the thread triangular port bottom surface of the self-tapping section is gradually flush with the triangular guide head end surface; the thread cross section of the machine thread section is trapezoidal or circular, used for screwing connection with the internal thread tapped by the self-tapping section. The utility model integrates the self-tapping function and the reliable connection function of machine thread on a single fastener, saves the cumbersome process of pre-preparing internal thread holes, significantly improves the assembly efficiency, reduces the production cost, and is especially suitable for batch production and automatic assembly scenes.

Description

Technical Field

[0001] This utility model relates to the field of fastener technology, and in particular to a fastener that integrates a self-tapping screw and a machine screw thread. Background Technology

[0002] In mechanical connections, fasteners such as screws and bolts are widely used to connect components. In existing technology, self-tapping fasteners can self-tap to form internal threads within smooth holes; however, these fasteners typically have low strength and are not interchangeable with standard machine threads. Machine thread fasteners, on the other hand, require pre-machining of the internal threads, increasing the process and cost. Therefore, there is a need for a fastener that can both self-tap and engage with machine threads, simplifying the installation process and improving connection reliability. Utility Model Content

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fastener that integrates self-tapping screw and machine thread. It can self-tap and form internal thread in the smooth hole and can be screwed into standard machine thread to achieve a fast and reliable connection.

[0004] To achieve the above objectives, this utility model adopts the following technical solution: a fastener integrating a self-tapping screw and a machine thread, comprising a rod portion, which is divided into a self-tapping screw segment and a machine thread segment from front to back; the rod portion located in the self-tapping screw segment is triangular, and a triangular guide head is provided at the front end of the rod portion; the thread cross-section of the self-tapping screw segment is triangular, used to form an internal thread by self-tapping within a smooth hole, and the bottom surface of the triangular end of the self-tapping screw segment gradually becomes flush with the end face of the triangular guide head; the thread cross-section of the machine thread segment is trapezoidal or circular, used to engage with the internal thread tapped by the self-tapping screw segment.

[0005] Furthermore, the outer diameter of the self-tapping screw segment gradually increases from the front end to the rear end, and the outer diameter of the thread at the rear end of the self-tapping screw segment gradually becomes equal to the outer diameter of the thread of the machine screw segment.

[0006] Furthermore, the length of the self-tapping screw segment is 1 / 3 to 1 / 2 of the total engagement length of the fastener.

[0007] Furthermore, the self-tapping screw segment has a tapered thread, with its large end close to the machine thread segment and its small end located at the front end of the fastener.

[0008] Furthermore, the pitch and thread angle of the thread of the machine thread section match those of the internal thread formed by the tapping of the self-tapping thread section.

[0009] Furthermore, a nut is provided on the rod portion away from the triangular guide head.

[0010] Furthermore, the fastener is made of alloy steel, and the surface hardness of the self-tapping screw section is higher than that of the machine thread section.

[0011] Furthermore, the tip of the triangular guide head has a flat or dome structure.

[0012] Furthermore, the thread angle of the triangular thread in the self-tapping segment is 30° to 60°.

[0013] The beneficial effects of this utility model are:

[0014] 1. By integrating the self-tapping screw section and the machine thread section, the fastener can self-tap to form an internal thread in the smooth hole. Then, the machine thread section engages with the tapped internal thread, avoiding the pre-tapping process and improving installation efficiency.

[0015] 2. The triangular thread and triangular guide head design of the self-tapping section make the tapping process smooth, reduce resistance, and extend the life of the fastener.

[0016] 3. The internal threads formed by the machine thread section and the self-tapping thread section are matched to ensure connection strength and high reliability.

[0017] 4. The self-tapping thread section has high hardness and good wear resistance, while the machine thread section has good toughness, resulting in optimized overall performance. Attached Figure Description

[0018] Figure 1 This is the front view of the present invention;

[0019] Figure 2 This is the right view of the present invention;

[0020] Figure 3 This is a structural schematic diagram of the present invention from one perspective. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0022] like Figure 1 , Figure 2 and Figure 3As shown, this utility model provides a fastener that integrates a self-tapping screw and a machine thread, which can be a screw or a bolt. Its overall structure includes a rod 1, which is divided into a self-tapping section 2 and a machine thread section 3 from front to back. A triangular guide head 4 is provided at the front end of the rod 1. The tip of the triangular guide head 4 has a flat-top structure. This design effectively prevents slippage or excessive indentation on the workpiece surface when tapping begins, ensuring the stability of the initial tapping. In other embodiments, the tip of the triangular guide head 4 has a rounded dome structure to adapt to the cutting characteristics of different materials.

[0023] The cross-section of the shank of self-tapping segment 2 is triangular, and the cross-section of the thread formed on it is also triangular (see...). Figure 3 The thread angle α of the triangular thread is preferably between 30° and 60°, for example, 45°. This sharp thread profile allows the self-tapping segment 2 to easily cut into the open hole of the workpiece material (such as plastic, aluminum alloy, or thin steel plate) during rotation, compressing and forming a matching internal thread. The thread of the self-tapping segment 2 is a tapered thread, with the outer diameter of the thread gradually increasing from its front end (small end) to its rear end (large end), and the outer diameter of the thread at its rear end gradually transitions to be equal to the outer diameter of the thread of the machine thread segment 3. To further optimize the tapping performance, the outer diameter of the thread of the self-tapping segment 2 can be slightly smaller than the outer diameter of the thread of the machine thread segment 3, with the difference controlled between 0.05 mm and 0.20 mm, for example, 0.10 mm. This provides the necessary chip space for the tapping process and reduces the rotational torque.

[0024] The length L1 of the self-tapping section 2 is designed to be 1 / 3 to 1 / 2 of the total engagement length of the fastener. This length is sufficient to fully tap a sufficiently strong internal thread within the smooth hole, without increasing unnecessary manufacturing costs and rotational resistance due to an excessively long self-tapping section.

[0025] The cross-section of the machine thread section 3 is a standard trapezoid or circle, such as a metric thread conforming to national standards. Its pitch and thread angle perfectly match the internal thread tapped by the self-tapping section 2 in the smooth hole. After the self-tapping section 2 completes tapping, the machine thread section 3 can be smoothly screwed into the formed internal thread, achieving a reliable connection of the standard machine thread. A nut 10 is provided at the end of the shank 1 away from the triangular guide head 4 for rotating the fastener. The nut 10 can be any suitable form such as a hexagonal head, pan head, or countersunk head, used to apply torque.

[0026] In terms of materials, the fastener is made of low-carbon steel or low-carbon alloy steel. To balance the cutting performance and overall toughness of the self-tapping screw, the fastener undergoes differentiated heat treatment: the surface hardness of the self-tapping screw section 2 is higher than that of the machine thread section 3. For example, the hardness of the self-tapping screw section 2 after quenching and tempering can reach HRC 45-50, while the hardness of the machine thread section 3 can be controlled at HRC 30-35. This ensures both the wear resistance and tapping ability of the self-tapping screw section and maintains good fatigue strength and toughness of the machine thread section.

[0027] During installation, the operator aligns the triangular guide head 4 at the front end of the fastener with the pre-drilled hole on the workpiece, and then rotates the nut 5 using a wrench or other tools. The triangular guide head 4 is first inserted and positioned, and then the triangular tapered thread of the self-tapping section 2 begins to cut into the hole wall material, forming an internal thread that matches its own tooth profile through compression and slight cutting. As the fastener continues to be screwed in, the self-tapping section 2 completes the tapping process, and the outer diameter of its thread at the end perfectly matches the size of the hole. Immediately afterwards, the standard-sized machine thread section 3 smoothly screws into the internal thread just formed by the self-tapping section 2 until the predetermined tightening torque is reached, completing the entire installation process.

[0028] In summary, this utility model integrates the functions of self-tapping screws and machine threads into a single fastener, simplifying the assembly process, improving efficiency, and ensuring the reliability of the connection joint. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

Claims

1. A fastener integrating a self-tapping screw and a machine thread, comprising a shank (1), characterized in that: The rod (1) is divided into a self-tapping section (2) and a machine thread section (3) from front to back. The rod (1) located in the self-tapping section (2) is triangular, and a triangular guide head (4) is provided at the front end of the rod (1). The thread cross-section of the self-tapping section (2) is triangular, which is used to form an internal thread by self-tapping in the hole. The bottom surface of the thread triangle port of the self-tapping section (2) is gradually flush with the end face of the triangular guide head (4). The thread cross-section of the machine thread section (3) is trapezoidal or circular, which is used to engage with the internal thread tapped by the self-tapping section (2).

2. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, The outer diameter of the self-tapping screw section (2) gradually increases from the front end to the rear end, and the outer diameter of the thread at the rear end of the self-tapping screw section (2) gradually becomes equal to the outer diameter of the thread of the machine screw section (3).

3. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, The length (L1) of the self-tapping screw segment (2) is 1 / 3 to 1 / 2 of the total engagement length of the fastener.

4. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, The self-tapping screw section (2) has a tapered thread, with its large end close to the machine thread section (3) and its small end located at the front end of the fastener.

5. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, The thread of the machine thread section (3) matches the pitch and tooth angle of the internal thread formed by the tapping of the self-tapping thread section (2).

6. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, A nut (10) is provided on the rod portion (1) at the end away from the triangular guide head (4).

7. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, The fastener is made of alloy steel, and the surface hardness of the self-tapping screw section (2) is higher than the surface hardness of the machine thread section (3).

8. The fastener integrating self-tapping screw and machine thread as described in claim 1, characterized in that, The tip of the triangular guide head (4) has a flat or dome structure.

9. The fastener integrating self-tapping screw and machine thread according to claim 1, characterized in that, The tooth angle of the triangular thread of the self-tapping section (2) is 30° to 60°.

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