Self-tapping dovetail screw

Abstract

This utility model discloses a self-tapping dovetail screw, belonging to the field of screw technology. The self-tapping dovetail screw of this utility model includes a threaded portion and a dovetail portion. A nut engages with the threaded portion. The dovetail portion includes a main structure and a dovetail structure. The dovetail structure is formed on the main structure. The diameter of the main structure is 0.1-0.3 mm smaller than the nominal inner diameter of the nut, and the taper of the tapered structure is 15°-25°. This utility model's self-tapping dovetail screw solves the technical problem of traditional dovetail screws being unable to fit nuts by designing the diameter of the main structure of the dovetail portion to be smaller than the nominal inner diameter of the nut and using a tapered structure to allow a standard nut to be smoothly inserted from the tail. The flattening treatment of the external thread end and the arc transition design enable the internal and external threads of the nut to gradually engage, avoiding instantaneous stress concentration. Combined with the stress dispersion design of the flattened area, the risk of stress concentration is significantly reduced.

Description

Technical Field

[0001] This utility model relates to the field of screw technology, and more specifically, to self-tapping dovetail screws. Background Technology

[0002] Existing dovetail screws cannot be fitted with nuts, and screws fitted with nuts do not have self-tapping capabilities. However, existing air ducts require screws with nuts for fixing, which necessitates drilling holes first, then inserting the screws, and finally fitting the nuts, making the installation quite cumbersome. Utility Model Content

[0003] The purpose of this invention is to overcome the shortcomings of the prior art by providing a self-tapping dovetail screw to solve the above-mentioned deficiencies.

[0004] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0005] The self-tapping dovetail screw of this utility model includes a threaded part and a dovetail part. A nut is engaged on the threaded part. The dovetail part includes a main structure and a dovetail structure. The dovetail structure is provided on the main structure. The diameter of the main structure is 0.1-0.3mm smaller than the nominal inner diameter of the nut. The taper of the tapered structure is 15°-25°.

[0006] Preferably, the threaded portion includes a screw and an external thread, the outer wall of the screw is uniformly provided with external threads, and the upper end of the screw is provided with a nut.

[0007] Preferably, the surface roughness Ra of the main structure is ≤3.2μm, and it is connected to the screw by a C0.5 chamfer.

[0008] Preferably, the dovetail angle of the dovetail structure is 60°±1°, the depth is 0.4-0.6 times the pitch, and the phase difference with the end of the external thread is ≥30°.

[0009] Preferably, the end of the external thread is provided with a flattening treatment area, the flattening amount is ≥0.2 times the thread height, and the end is provided with a R0.3mm rounded transition.

[0010] Preferably, the lower end of the main structure is provided with a tapered structure, and after the nut is introduced from the tapered structure, it forms a clearance fit with the main structure, with a clearance of 0.1-0.3mm.

[0011] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0012] This utility model of a self-tapping dovetail screw solves the technical problem of traditional dovetail screws being unable to adapt to nuts by designing the diameter of the main structure of the dovetail to be smaller than the nominal inner diameter of the nut and using a tapered structure to allow the standard nut to be smoothly inserted from the tail. The flattening treatment of the external thread end and the arc transition design enable the internal and external threads of the nut to gradually mesh, avoiding instantaneous stress concentration. The phase difference between the thread end and the dovetail start end is ≥30°. Combined with the stress dispersion design of the flattened area, the risk of stress concentration is significantly reduced. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the self-tapping dovetail screw of this utility model;

[0014] Figure 2 This is a front view of the self-tapping dovetail screw of this utility model;

[0015] Figure 3 This is an enlarged view of section A of this utility model.

[0016] In the diagram: 1. Threaded part; 11. Screw; 111. Nut; 12. External thread; 2. Dovetail part; 21. Main structure; 211. Tapered structure; 22. Dovetail structure; 3. Nut. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings.

[0019] Combination Figures 1-3 The self-tapping dovetail screw of this utility model includes a threaded part 1 and a dovetail part 2. The lower end of the threaded part 1 is fixedly connected to the upper end of the dovetail part 2, and a nut 3 is engaged on the threaded part 1.

[0020] Specifically, the threaded part 1 includes a screw 11 and an external thread 12 provided on the outside of the screw 11. The external thread 12 is used to fix the nut 3. A nut 111 is fixedly connected to the upper end of the screw 11. The nut 111 drives the screw 11 to rotate and limits the upper end of the screw 11.

[0021] More specifically, the dovetail portion 2 includes a main structure 21 and a dovetail structure 22. The upper end of the main structure 21 is fixedly connected to the lower end of the screw 11. The dovetail structure 22 is provided on the main structure 21. A tapered structure 211 is provided at the lower end of the main structure 21. The dovetail structure 22 starts from the tapered structure 211, extends to the end of the main structure 21, and is connected to one end of the external thread 12. The surface roughness Ra of the main structure 21 is ≤3.2μm. The dovetail angle of the dovetail structure 22 is 60°±1°, and the depth is 0.4-0.6 times the pitch.

[0022] It should be noted that the end of the external thread 12 near the dovetail structure 22 is flattened at the tooth tip, with a flattening amount ≥ 0.2 times the tooth height. The internal thread of the nut 3 gradually engages with the external thread 12, and the auxiliary nut 3 stably engages with the external thread 12. A 0.3mm radius arc transition is set at the end of the flattened area, and the phase difference between the end of the thread and the beginning of the dovetail is ≥ 30° to avoid stress superposition.

[0023] In addition, the taper of the tapered structure 211 is 15°-25°, the upper diameter of the main structure 21 is smaller than the diameter of the screw 11, and the main structure 21 and the screw 11 are connected by a chamfer. The diameter of the main structure 21 is 0.1-0.3mm smaller than the nominal inner diameter of the nut.

[0024] Working process: When in use, the threaded part 1 is screwed on by the nut 111, which drives the dovetail part 2 to self-tap the air inlet pipe and drives the threaded part 1 to penetrate the side wall of the air pipe. The nut 3 is introduced from the tapered structure 211 of the dovetail part 2. The diameter of the main structure 21 is 0.1-0.3mm smaller than the inner diameter of the nut, so as to achieve self-centering guidance. When it reaches the flattened treatment area at one end of the external thread 12, the internal thread of the nut 3 gradually engages with the external thread 12 to achieve locking.

[0025] It should be noted that, in this document, relational terms such as "first" and "second" are used only 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 process, method, article, or apparatus.

[0026] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A self-tapping dovetail screw comprising a threaded portion (1) and a dovetail portion (2), characterized in that: The threaded part (1) is engaged with a nut (3), and the dovetail part (2) includes a main structure (21) and a dovetail structure (22). The dovetail structure (22) is provided on the main structure (21). The diameter of the main structure (21) is 0.1-0.3 mm smaller than the nominal inner diameter of the nut (3), and the taper of the tapered structure (211) is 15°-25°.

2. A self-tapping dovetail screw according to claim 1, wherein: The threaded part (1) includes a screw (11) and an external thread (12). The outer wall of the screw (11) is uniformly provided with the external thread (12), and the upper end of the screw (11) is provided with a nut (111).

3. A self-tapping dovetail screw according to claim 2, wherein: The surface roughness Ra of the main structure (21) is ≤3.2μm, and it is connected to the screw (11) by a C0.5 chamfer.

4. A self-tapping dovetail screw according to claim 2, wherein: The dovetail angle of the dovetail structure (22) is 60°±1°, the depth is 0.4-0.6 times the pitch, and the phase difference between the dovetail structure (22) and the end of the external thread (12) is ≥30°.

5. A self-tapping dovetail screw according to claim 2, wherein: The external thread (12) has a flattening treatment area at the end, with a flattening amount ≥ 0.2 times the thread height, and a R0.3mm round arc transition at the end.

6. A self-tapping dovetail screw according to claim 1, wherein: The lower end of the main structure (21) is provided with a tapered structure (211). After the nut (3) is introduced from the tapered structure (211), it forms a clearance fit with the main structure (21), with a clearance of 0.1-0.3 mm.

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