Self-tapping fastener and connecting assembly

Abstract

The invention discloses a self-tapping fastener and a connecting assembly. The self-tapping fastener comprises a driving part, a flange part, a thread part, a guide cone part and a tail part which are connected from top to bottom. And the thread part is provided with an external thread, so that a thread is self-tapped on the metal plate. The guide cone part is of a frustum structure with the outer diameter gradually reduced from top to bottom, so that the reaming action is performed step by step, the horizontal cross section of the guide cone part is of an eccentric three-impeller structure, the eccentric three-impeller structure comprises three convex arcs and three concave arcs, and the convex arcs are connected with the two adjacent concave arcs, so that the convex arcs and the concave arcs alternately form a polygon; the eccentric three-blade wheel structure is adopted, the sheet metal deformation efficiency is improved, the eccentric direction of the eccentric three-blade wheel structure is opposite to the spiral direction of the external threads, and cuttings are not prone to being accumulated, blocked and sintered. And the horizontal cross section of the tail part is gradually reduced from top to bottom, thereby facilitating initial work into a metal plate.

Description

Technical Field

[0001] The present invention relates to the field of fasteners, and particularly to a self-tapping fastener and a connection assembly Background Art

[0002] In existing self-tapping fasteners, a tail is provided at the lower end of the threaded portion. The tail is generally a cone with a smooth outer surface. During self-tapping, there are problems such as low sheet metal deformation efficiency, chip accumulation and blockage, and sintering, which are not conducive to subsequent self-tapping of the threaded portion Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects or problems in the background art or to provide a material basis for overcoming the above-mentioned defects or problems in the background art, and to provide a self-tapping fastener and a connection assembly

[0004] To achieve the above purpose, the present invention and its preferred embodiments adopt the following technical solutions, but the embodiments are not limited to the following solutions

[0005] Solution 1, a self-tapping fastener, comprising a

[0006] driving portion connected from top to bottom

[0007] flange portion

[0008] threaded portion, which is provided with an external thread

[0009] guide cone portion, which is a frustum structure, whose outer diameter size gradually decreases from top to bottom, and its horizontal cross-section is an eccentric three-impeller structure. The eccentric direction of the eccentric three-impeller structure is opposite to the spiral direction of the external thread; the eccentric three-impeller structure includes three convex arcs and three concave arcs, and the convex arcs connect adjacent two concave arcs

[0010] tail portion, whose size gradually decreases from top to bottom

[0011] Solution 2, based on Solution 1, the outer wall of the driving portion is provided with a driving surface, and the driving portion is further provided with a driving groove, and the notch direction of the driving groove is upward

[0012] Solution 3, based on Solution 1, the flange portion includes a flange body and a protrusion protruding radially from the flange body along the flange body. The flange body is provided with a downward supporting surface, and there is a gap between the bottom surface of the protrusion and the supporting surface

[0013] Solution 4, based on Solution 3, the bottom surface and / or the side wall of the protrusion is provided with a lace

[0014] Solution Five, based on Solution One, the threaded portion includes a first external thread, a second external thread, and a third external thread arranged from top to bottom. The horizontal cross-section of the first external thread is circular. Both the second external thread and the third external thread are triangular rod threads. The outer diameter of the second external thread remains unchanged from top to bottom, and the outer diameter of the third external thread gradually decreases from top to bottom.

[0015] Solution Six, based on Solution One, further includes a rounding portion. The two ends of the rounding portion are respectively connected to the guiding conical portion and the threaded portion. The rounding portion is a cylindrical structure. The outer wall of the rounding portion is a smooth surface, and its outer diameter remains unchanged from top to bottom.

[0016] Solution Seven, based on Solution One, the tail portion is a triangular pyramid structure. The orthographic projection contour of the tail portion includes a horizontal line segment and arcs connected to both ends of the horizontal line segment. The distances between the two arcs and the axis of the self-tapping fastener gradually decrease from top to bottom until the two arcs are connected.

[0017] The horizontal cross-section of the tail portion is circular or triangular. The difference between the diameter of the inscribed circle and the diameter of the circumscribed circle of the horizontal cross-section of the tail portion is (0 - 0.5)P, where P is the pitch of the thread of the threaded portion.

[0018] Solution Eight, based on Solution One, the first endpoint of the convex arc starts from the circumscribed circle of the eccentric three-blade impeller structure, and the second endpoint is located inside the circumscribed circle. The concave arc is adapted to be connected to the inscribed circle of the eccentric three-blade impeller structure. The tangent of the first endpoint and the first tangent of the circumscribed circle at the first endpoint form a first clearance angle. The tangent of the concave arc at the first endpoint and the line connecting the first endpoint and the center of the circumscribed circle form a front angle, and the front angle is an acute angle.

[0019] Solution Nine, based on Solution Eight, the convex arc includes a first convex arc and a second convex arc. The first convex arc is provided with the first endpoint. The second convex arc is connected to the first convex arc and is provided with the second endpoint. The tangent at the connection of the second convex arc and the first convex arc and the first tangent form a second clearance angle, and the second clearance angle is greater than the first clearance angle. The horizontal normal length of the first convex arc is the blade width.

[0020] Solution Ten, a connection assembly includes a sheet metal and a self-tapping fastener according to any one of Solutions One to Nine. The self-tapping fastener is in threaded cooperation with the sheet metal.

[0021] As described above for the present invention and its preferred embodiments, compared with the prior art, the technical solutions and their preferred embodiments of the present invention have the following beneficial effects due to the following technical means:

[0022] 1. In Solution 1 and its preferred embodiments, a self-tapping fastener includes a driving part, a flange part, a threaded part, a guiding cone part, and a tail part connected from top to bottom. The driving part is used for an external part to drive the self-tapping fastener to rotate, so as to achieve self-tapping. The flange part is used to abut against the sheet metal after self-tapping is completed to achieve support. The threaded part is provided with an external thread to tap a thread on the sheet metal. The guiding cone part is a frustum structure with an outer diameter gradually decreasing from top to bottom, so as to gradually perform the hole expansion action. And the horizontal cross-section of the guiding cone part is an eccentric three-blade impeller structure, which includes three convex arcs and three concave arcs. The convex arcs connect two adjacent concave arcs, so that the convex arcs and the concave arcs alternately form a polygon, that is, the eccentric three-blade impeller structure, which improves the deformation efficiency of the sheet metal. And the eccentric direction of the eccentric three-blade impeller structure is opposite to the spiral direction of the external thread, and chips are not easily accumulated, blocked, or sintered. The tail part has a gradually decreasing size from top to bottom, so as to facilitate the initial penetration into the sheet metal.

[0023] 2. In Solution 2 and its preferred embodiments, the outer wall of the driving part is provided with a driving surface, and the driving part is also provided with a driving groove with an upward notch direction, so as to achieve dual driving inside and outside.

[0024] ① Limited by the assembly space, the head of this product (including the driving part and the flange part) needs to adopt a thin design. After the head is thinned, the wrenching strength in the case of conventional single driving, only internal driving or only external driving is reduced. However, the dual driving design inside and outside can increase the wrenching strength and provide a higher driving torque.

[0025] ② Apply torque from both the inside and the outside at the same time, so that the self-tapping fastener is more evenly stressed when being tightened or loosened.

[0026] ③ It has stronger applicability and can be applicable to a variety of driving heads, with more flexibility.

[0027] ④ Protect the self-tapping fastener and the workpiece, reduce surface damage, and improve the stability of the connection process.

[0028] ⑤ Improve the installation efficiency. The dual driving inside and outside can effectively prevent situations that affect the installation efficiency, such as the driving part slipping and the nail falling off, so as to ensure the installation efficiency.

[0029] ⑥ Reduce the product weight and save materials, so that the head can be thinner and the diameter of the driving part can be smaller. And the design of the driving groove also realizes weight reduction.

[0030] 3. In Solution 3 and its preferred embodiments, the flange portion includes a flange body and a protrusion protruding radially from the flange body along the flange body. The flange body is provided with a downward-facing support surface, and there is a gap between the bottom surface of the protrusion and the support surface, which has the following beneficial effects: When used as a detection scale for the tightening degree of the flexible connection, since there is a gap between the bottom surface of the protrusion and the support surface, when the clamping member is made of rubber or other materials, the degree to which the support surface sinks into the clamping member (positioning reference line) can be detected through the protrusion after tightening. To prevent surface damage, the outer diameter of the protrusion is larger than the outer diameter of the support surface, which can prevent the support surface from being knocked, scratched, etc. during transportation, assembly, and use to a certain extent, maintain the flatness of the support surface, and thus ensure the connection and sealing performance.

[0031] 4. In Solution 4 and its preferred embodiments, the bottom surface and / or side wall of the protrusion is provided with a lace. Limited by the assembly space, generally, after the self-tapping fastener is tightened and connected, the manufacturer information cannot be identified and confirmed. The lace can be set into a unique pattern for identifying and confirming the manufacturer information from the side. The lace can increase the friction force on the outer edge of the flange portion, facilitating the grasping and conveying of the self-tapping fastener. It is convenient for installation and positioning. During the installation process, the wavy pattern of the lace can be used as a visual identifier or positioning reference. When used as a positioning reference (the same as above), it can help the installer align the flange more accurately, ensure the installation accuracy, and improve the installation quality. The lace has the function of beautifying the appearance and decoration, enhancing the overall visual effect.

[0032] 5. In Solution 5 and its preferred embodiments, the threaded portion includes a first external thread, a second external thread, and a third external thread arranged from top to bottom. The horizontal cross-section of the first external thread is circular, and both the second external thread and the third external thread are triangular rod threads. The outer diameter of the second external thread remains unchanged from top to bottom, and the outer diameter of the third external thread gradually decreases from top to bottom. The function of the third external thread is to guide the threaded portion into the sheet metal hole. The third external thread contacts the sheet metal hole from small to large, dispersing the force and avoiding damage to the threaded portion due to too rapid penetration and deformation through the hole. The second external thread further refines the thread size and thread surface state, so that the quality of the threaded hole formed can meet the final application. The first external thread will finally be screwed into the self-tapping sheet metal threaded hole to clamp the sheet metal and complete the fastening connection.

[0033] 6. In Solution 6 and its preferred embodiments, it further includes a rounding portion, and both ends of the rounding portion are respectively connected to the guiding cone portion and the threaded portion; the rounding portion is a cylindrical structure, the outer wall of the rounding portion is a smooth surface, and its outer diameter remains unchanged from top to bottom. The function of the rounding portion is to further perform secondary correction on the hole wall that has been reamed by the guiding cone portion to stabilize the hole diameter size. Since the guiding cone portion is a frustum structure that is larger at the top and smaller at the bottom, the hole diameter has been continuously enlarged during the penetration process and has not been stably trimmed and maintained, so the hole diameter will shrink and deform, which is not conducive to subsequent threading.

[0034] 7. In Solution Seven and its preferred embodiments, the tail is in the shape of a triangular pyramid. The orthographic projection contour of the tail includes a horizontal line segment and arcs connected to both ends of the horizontal line segment. The distance between the two arcs gradually decreases from top to bottom along the axis of the self-tapping fastener until the two arcs connect to form a conical tip. The function of the conical tip is to guide the sheet metal and generate a certain frictional force with the sheet metal. The diameter of the horizontal line segment is the largest, approximately equal to the minor diameter of the external thread. The horizontal cross-section of the tail is circular or triangular. When the horizontal cross-section of the tail is triangular, it is formed by connecting three outwardly convex arcs. The difference between the diameter of the inscribed circle and the diameter of the circumscribed circle of the horizontal cross-section of the tail is (0 - 0.5)P, so that the horizontal cross-section of the tail is approximately circular, increasing the contact area with the sheet metal, thereby increasing the frictional resistance and ensuring the generation of sufficient frictional heat for the stretching deformation of the sheet metal. At the same time, the three ridge lines can also improve the deformation efficiency to a certain extent.

[0035] 8. In Solution Eight and its preferred embodiments, the first endpoint of the convex arc starts from the circumscribed circle of the eccentric three-impeller structure, and the second endpoint is located inside the circumscribed circle, so that there is a certain gap between the convex arc and the circumscribed circle, that is, a first clearance angle is formed between the tangent line of the first endpoint and the first tangent line of the circumscribed circle at the first endpoint, thereby reducing the contact area between the guiding cone part and the sheet metal hole, improving the sheet metal deformation efficiency, and at the same time reducing the risk of chip accumulation and sintering.

[0036] The concave arc is adapted to be connected to the inscribed circle of the eccentric three-impeller structure; the tangent line of the concave arc at the first endpoint forms a front angle with the line connecting the first endpoint and the center of the circumscribed circle. The front angle is an acute angle. The sharp front angle can provide sheet metal deformation efficiency, reduce the extrusion force, reduce power consumption, and reasonably increasing the front angle can reduce the extrusion deformation force and frictional force, lower the processing temperature. The concave arc area can also accommodate debris, making the tapping process smoother, thereby reducing the surface roughness of the hole wall, improving the surface quality and subsequent thread quality. This structure has the function of trimming and cleaning the hole wall, preparing for subsequent tapping, and reducing the processing torque and the requirement for hole accuracy.

[0037] 9. In Solution Nine and its preferred embodiments, the convex arc includes a first convex arc and a second convex arc. The first convex arc has a first endpoint, the second convex arc is connected to the first convex arc and has a second endpoint. The tangent line at the connection of the second convex arc and the first convex arc forms a second clearance angle with the first tangent line. The second clearance angle is greater than the first clearance angle (the second convex arc is equivalent to a finishing arc design); the horizontal normal length of the first convex arc is the edge width. Compared with the structure with only one convex arc, this structure can reduce the angle of the first clearance angle and increase the edge width, thereby being beneficial to improving the strength at the tip of this structure and being more suitable for tapping high-strength sheet metal materials.

[0038] 10. In Solution Ten and its preferred embodiments, a connection component includes a sheet metal and the above-mentioned self-tapping fastener. The self-tapping fastener is in threaded fit with the sheet metal and has the beneficial effects brought by the above-mentioned self-tapping fastener. Brief Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 Front view of the self-tapping fastener in Embodiment 1;

[0041] Figure 2 Schematic diagram of the cooperation between the self-tapping fastener and the sheet metal in Embodiment 1;

[0042] Figure 3 Schematic diagram of the view from Angle A in Embodiment 1;

[0043] Figure 4 Schematic diagram of the view from Angle B in Embodiment 1;

[0044] Figure 5 For Figure 1 Cross-sectional view taken along C-C in;

[0045] Figure 6 For Figure 1 Cross-sectional view taken along D-D in;

[0046] Figure 7 For Figure 1 Cross-sectional view taken along F-F in;

[0047] Figure 8 For Figure 7 Enlarged view of;

[0048] Figure 9 Preferred schematic diagram of the eccentric three-impeller;

[0049] Figure 10 For Figure 9 Enlarged view of;

[0050] Figure 11 For Figure 1 Cross-sectional view taken along G-G in;

[0051] Figure 12 Schematic diagram of the tail entering the sheet metal;

[0052] Figure 13 Schematic diagram of the guide cone part entering the sheet metal;

[0053] Figure 14 Schematic diagram of the threaded part entering the sheet metal.

[0054] Main reference numeral description:

[0055] 1 Driving part; 11 Outer driving part; 111 Driving surface; 12 Inner driving part; 121 Driving groove; 13 Outer chamfer;

[0056] 2 Flange part; 21 Flange body; 211 Support surface; 22 Protrusion; 221 Lace;

[0057] 3 Thread part; 31 Functional part; 311 First external thread; 32 Thread tapping part; 321 Finishing part; 3211 Second external thread; 322 Guide part; 3221 Third external thread;

[0058] 4 Smoothing part;

[0059] 5 Guide cone part; 51 Convex arc; 511 First endpoint; 512 Second endpoint; 513 First tangent; 514 First clearance angle; 515 Second clearance angle; 516 First convex arc; 517 Second convex arc; 518 Edge width;

[0060] 52 Concave arc; 521 Front angle;

[0061] 6 Tail part; 61 Horizontal line segment; 62 Arc;

[0062] 7 Sheet metal; Detailed implementation mode

[0063] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are the preferred embodiments of the present invention and should not be regarded as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0064] In the claims, description and above-mentioned accompanying drawings of the present invention, unless otherwise clearly defined, when using terms such as "first", "second" or "third", etc., they are all used to distinguish different objects and not for describing a specific order.

[0065] In the claims, description and above-mentioned accompanying drawings of the present invention, unless otherwise clearly defined, for orientation terms, when using terms such as "center", "horizontal", "longitudinal", "level", "vertical", "top", "bottom", "inner", "outer", "up", "down", "front", "rear", "left", "right", "clockwise", "counterclockwise", etc. to indicate the orientation or position relationship, it is based on the orientation and position relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as limiting the specific protection scope of the present invention.

[0066] In the claims, the description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, when using the terms "fixed connection" or "fixedly connected", it should be understood in a broad sense, that is, any connection method without displacement relationship and relative rotation relationship between the two, that is, it includes non-detachable fixed connection, detachable fixed connection, being integrally formed, and being fixed connected through other devices or components.

[0067] In the claims, the description and the above-mentioned drawings of the present invention, when using the terms "comprising", "having" and their variants, are intended to mean "including but not limited to".

[0068] Embodiment 1

[0069] Reference Figures 1-14 , a self-tapping fastener, comprising a driving part 1, a flange part 2, a threaded part 3, a rounding part 4, a guiding cone part 5 and a tail part 6 connected from top to bottom.

[0070] Reference Figure 2 、 Figure 4 , the driving part 1 includes an outer driving part 11 and an inner driving part 12, and the outer driving part 11 and the inner driving part 12 are transitioned through an outer chamfer 13. The outer driving part 11 is formed by the outer side wall of the driving part 1, and the outer driving part 11 is provided with a driving surface 111 to form an outer drive. The driving surface 111 can be a concave arc surface, a convex arc surface, a vertical surface, etc. In this embodiment, the outer driving part 11 is of an outer flower shape (having a plurality of convex parts protruding outward, and the convex part is transitioned through the outer chamfer 13 with the top surface of the driving part 1), and can be a four-corner, six-corner, eight-corner, etc. structure.

[0071] The inner driving part 12 is further provided with a driving groove 121, and the notch direction of the driving groove 121 is upward to form an inner drive. In this embodiment, the driving groove 121 is of an inner flower shape (the groove wall of the driving groove 121 with a plurality of convex parts protruding inward).

[0072] Reference Figure 2 、 Figure 3 , the flange part 2 includes a flange body 21 and a protrusion 22. The flange body 21 is provided with a downward support surface 211, and the support surface 211 is adapted to abut against the sheet metal 7. The protrusion 22 protrudes radially outward from the flange body 21, so the protrusion 22 is more protruding than the outer edge of the support surface 211, that is, the outer diameter of the protrusion 22 is greater than the outer diameter of the support surface 211. And there is a gap between the bottom surface of the protrusion 22 and the support surface 211. The bottom surface or the side wall of the protrusion 22 is provided with a lace 221.

[0073] Reference Figure 1 、 Figure 5 、 Figure 6, the threaded portion 3 is provided with an external thread. Specifically, the threaded portion 3 includes a functional portion 31 and a tapping portion 32 connected in sequence from top to bottom. The functional portion 31 is provided with a first external thread 311. The first external thread 311 is a common metric thread and defines the major diameter of the external thread, the pitch diameter of the external thread, the minor diameter of the external thread, and the thread pitch. The horizontal cross-section of the first external thread 311 is circular. The horizontal cross-section is the plane perpendicular to the up-down direction.

[0074] Reference Figure 6 , the tapping portion 32 is an overall triangular rod thread, reference Figure 1 , the tapping portion 32 includes a finishing portion 321 and a guiding portion 322. The finishing portion 321 is provided with a second external thread 3211, and the guiding portion 322 is provided with a third external thread 3221. The second external thread 3211 connects the first external thread 311 and the third external thread 3221. The outer diameter of the second external thread 3211 remains unchanged from top to bottom; the outer diameter of the third external thread 3221 gradually decreases from top to bottom, generally being a frustum structure with a larger upper part and a smaller lower part. The outer contour line of its front projection surface is a straight line, and the outer diameter of its upper end is the major diameter of the external thread.

[0075] Both ends of the rounding portion 4 are respectively connected to the tapered portion 5 and the threaded portion 3. The rounding portion 4 is connected to the upper end of the tapered portion 5. The rounding portion 4 is a cylindrical structure. The outer wall of the rounding portion 4 is a smooth surface, and the outer contour line of the front projection contour of the rounding portion 4 is a straight line. And the outer diameter of the rounding portion 4 remains unchanged from top to bottom. The diameter of the horizontal cross-section of the rounding portion 4 is approximately equal to the pitch diameter of the external thread. The axial length of the rounding portion 4 is approximately 1-2 times the thread pitch P.

[0076] The tapered portion 5 is a frustum structure with an outer diameter gradually decreasing from top to bottom. The lower end surface of the tapered portion 5 is connected to the upper end surface of the tail portion 6. The diameter of the upper end surface is larger than the diameter of the lower end surface, and the diameter of the upper end surface is approximately equal to the pitch diameter of the external thread.

[0077] The horizontal cross-section of the tapered portion 5 is an eccentric three-leaf impeller structure. The eccentric direction of the eccentric three-leaf impeller structure is opposite to the helical direction of the external thread (the helical directions of the second external thread 3211, the first external thread 311, and the third external thread 3221 are the same). For example, when the external thread is right-handed, the eccentric three-leaf impeller structure is eccentric to the left side of the axis (the center of gravity is on the left).

[0078] Reference Figure 7 , Figure 8, the eccentric three - impeller structure includes three convex arcs 51 and three concave arcs 52. The convex arcs 51 connect adjacent concave arcs 52. The first end point 511 of the convex arc 51 starts from the circumcircle of the eccentric three - impeller structure, and the second end point 512 is located inside the circumcircle; the concave arc 52 is adapted to be connected to the inscribed circle of the eccentric three - impeller structure. Among them, a first clearance angle 514 is formed between the tangent of the first end point 511 and the first tangent 513 of the circumcircle at the first end point 511; the tangent of the concave arc 52 at the first end point 511 and the connection line between the first end point 511 and the center of the circumcircle form a front angle 521, and the front angle 521 is an acute angle.

[0079] Preferably, referring to Figure 9 , Figure 10 , the convex arc 51 includes a first convex arc 516 and a second convex arc 517. The first convex arc 516 is provided with a first end point 511. The second convex arc 517 is connected to the first convex arc 516 and is provided with a second end point 512. The tangent at the connection of the second convex arc 517 and the first convex arc 516 and the first tangent 513 form a second clearance angle 515, and the second clearance angle 515 is greater than the first clearance angle 514; the horizontal normal length of the first convex arc 516 is the blade width 518. Among them, convex means protruding in the direction relatively far from the center of the circle, and concave means sunken in the direction close to the center of the circle.

[0080] Referring to Figure 1 、 Figure 11 , the size of the tail 6 gradually decreases from top to bottom. The tail 6 is a triangular pyramid structure. The orthographic projection contour of the tail 6 includes a horizontal line segment 61 and arcs 62 connected to both ends of the horizontal line segment 61. The distance between the two arcs 62 gradually decreases from top to bottom until the two arcs 62 are connected to form a conical tip. The function of the conical tip is to guide the sheet metal 7 and generate a certain frictional force with the sheet metal 7. The diameter of the horizontal line segment 61 is the largest and is approximately equal to the minor diameter of the external thread.

[0081] The horizontal cross - section of the tail 6 is circular or triangular. When the horizontal cross - section of the tail 6 is triangular, it is formed by connecting three outward - protruding arcs 62. Referring to Figure 11 , the difference between the diameter of the inscribed circle and the diameter of the circumcircle of the horizontal cross - section of the tail 6 is (0 - 0.5)P, so that the horizontal cross - section of the tail 6 is approximately circular, increasing the contact area with the sheet metal 7, thereby increasing the frictional resistance and ensuring the generation of sufficient frictional heat for the stretching deformation of the sheet metal 7. At the same time, the three ridge lines can also improve the deformation efficiency to a certain extent.

[0082] Compared with the prior art, the present embodiment has the following beneficial effects:

[0083] In an exemplary embodiment, a self-tapping fastener includes a driving portion 1, a flange portion 2, a threaded portion 3, a guiding conical portion 5, and a tail portion 6 that are connected from top to bottom. The driving portion 1 is used for an external part to drive the self-tapping fastener to rotate, so as to achieve self-tapping. The flange portion 2 is used to abut against the sheet metal 7 after self-tapping is completed to achieve support. The threaded portion 3 is provided with an external thread, so as to self-tap a thread on the sheet metal 7. The guiding conical portion 5 is a frustum structure with an outer diameter gradually decreasing from top to bottom, so as to gradually perform the action of reaming the hole. And the horizontal cross-section of the guiding conical portion 5 is an eccentric three-blade impeller structure. The eccentric three-blade impeller structure includes three convex arcs 51 and three concave arcs 52. The convex arcs 51 connect two adjacent concave arcs 52, so that the convex arcs 51 and the concave arcs 52 alternately form a polygon, that is, the eccentric three-blade impeller structure, which improves the deformation efficiency of the sheet metal 7. And the eccentric direction of the eccentric three-blade impeller structure is opposite to the spiral direction of the external thread, and chips are not easily accumulated, blocked, or sintered. The size of the tail portion 6 gradually decreases from top to bottom, so as to facilitate the initial insertion into the sheet metal 7.

[0084] In an exemplary embodiment, a driving surface 111 is provided on the outer wall of the driving portion 1, and the driving portion 1 is further provided with a driving groove 121, and the notch direction of the driving groove 121 is upward, so as to achieve dual driving inside and outside.

[0085] ① Limited by the assembly space, the head of this product (including the driving portion 1 and the flange portion 2) needs to adopt a thin design. After the head is thinned, the wrenching strength in the case of conventional single driving, only internal driving or only external driving is reduced. However, the dual driving design inside and outside can increase the wrenching strength and provide a higher driving torque.

[0086] ② Apply torque from both the inside and the outside simultaneously, so that the self-tapping fastener is more evenly stressed when being tightened or loosened.

[0087] ③ It has stronger applicability, can be applicable to a variety of driving heads, and has more flexibility.

[0088] ④ Protect the self-tapping fastener and the workpiece, reduce surface damage, and improve the stability of the connection process.

[0089] ⑤ Improve the installation efficiency. The dual driving inside and outside can effectively prevent situations that affect the installation efficiency, such as the driving portion 1 slipping off and the nail falling off, so as to ensure the installation efficiency.

[0090] ⑥ Reduce the product weight and save materials, so that the head can be thinner and the diameter of the driving portion 1 can be smaller. And the design of the driving groove 121 also realizes weight reduction.

[0091] In an exemplary embodiment, the flange portion 2 includes a flange body 21 and a protrusion 22 protruding radially from the flange body 21. The flange body 21 is provided with a downward support surface 211, and there is a gap between the bottom surface of the protrusion 22 and the support surface 211, having the following beneficial effects: When used as a detection scale for the tightening degree of a flexible connection, since there is a gap between the bottom surface of the protrusion 22 and the support surface 211, when the clamping member is made of rubber or the like, the degree to which the support surface 211 sinks into the clamping member (positioning reference line) can be detected through the protrusion 22 after tightening. To prevent surface damage, the outer diameter of the protrusion 22 is larger than the outer diameter of the support surface 211, which can prevent the support surface 211 from being bumped, scratched, etc. during transportation, assembly, and use to a certain extent, maintain the flatness of the support surface 211, and thus ensure the connection and sealing performance.

[0092] In an exemplary embodiment, the bottom surface and / or the side wall of the protrusion 22 is provided with a lace 221. Limited by the assembly space, generally, after the self-tapping fastener is tightened and connected, the manufacturer information cannot be identified and confirmed. The lace 221 can be set into a unique pattern for identifying and confirming the manufacturer information from the side. The lace 221 can increase the friction force on the outer edge of the flange portion 2, facilitating the grasping and conveying of the self-tapping fastener. Facilitating installation and positioning, during the installation process, the wavy pattern of the lace 221 can be used as a visual identifier or a positioning reference. When used as a positioning reference (the same as above), it can help the installer align the flange more accurately, ensure the installation accuracy, and improve the installation quality. The lace 221 has the function of beautifying the appearance and decoration, enhancing the overall visual effect.

[0093] In an exemplary embodiment, the threaded portion 3 includes a first external thread 311, a second external thread 3211, and a third external thread 3221 arranged from top to bottom. The horizontal cross-section of the first external thread 311 is circular, and both the second external thread 3211 and the third external thread 3221 are triangular rod threads. The outer diameter of the second external thread 3211 remains unchanged from top to bottom, and the outer diameter of the third external thread 3221 gradually decreases from top to bottom. The function of the third external thread 3221 is to guide the threaded portion 3 into the sheet metal hole. The third external thread 3221 contacts the sheet metal hole from small to large, dispersing the force and preventing damage to the threaded portion 3 due to too rapid penetration and deformation of the hole. The second external thread 3211 further refines the thread size and the thread surface state, so that the quality of the threaded hole tapped can meet the final application. And the first external thread 311 will finally be screwed into the threaded hole of the self-tapping sheet metal 7 to clamp the sheet metal 7 to complete the fastening connection.

[0094] In one exemplary embodiment, a rounding portion 4 is further included, with its ends connecting the guide cone portion 5 and the threaded portion 3, respectively. The rounding portion 4 is cylindrical, with a smooth outer wall and a constant outer diameter from top to bottom. The rounding portion 4 serves to further correct the hole wall, already expanded by the guide cone portion 5, to stabilize the hole diameter. Because the guide cone portion 5 is a frustum-shaped structure with a larger top and a smaller bottom, the hole diameter is continuously expanded during the tapping process. Without stable trimming and maintenance, the hole diameter will shrink and deform, hindering subsequent threading.

[0095] In an exemplary embodiment, the tail 6 is a triangular pyramid structure, and the orthographic projection profile of the tail 6 includes a horizontal line segment 61 and an arc 62 connected to the two ends of the horizontal line segment 61. The distance between the two arcs 62 and the axis of the self-tapping fastener gradually decreases from top to bottom until the two arcs 62 are connected to form a cone tip. The function of the cone tip is to guide the sheet metal 7 and generate a certain friction force with the sheet metal 7. The diameter of the horizontal line segment 61 is the largest, approximately equal to the minor diameter of the external thread. The horizontal cross-section of the tail 6 is circular or triangular. When the horizontal cross-section of the tail 6 is triangular, it is formed by connecting three outwardly protruding arcs 62. The difference between the inscribed circle diameter and the circumscribed circle diameter of the horizontal cross-section of the tail 6 is (0-0.5)P, so that the horizontal cross-section of the tail 6 is roughly circular, thereby increasing the contact area with the sheet metal 7, thereby increasing the friction resistance, ensuring that sufficient friction heat is generated, and facilitating the tensile deformation of the sheet metal 7. At the same time, the three ridges can also improve the deformation efficiency to a certain extent.

[0096] In an exemplary embodiment, the first endpoint 511 of the convex arc 51 starts from the circumscribed circle of the eccentric three-impeller structure, and the second endpoint 512 is located within the circumscribed circle, so that there is a certain gap between the convex arc 51 and the circumscribed circle, that is, a first clearance angle 514 is formed between the tangent of the first endpoint 511 and the first tangent 513 of the circumscribed circle at the first endpoint 511, thereby reducing the contact area between the guide cone 5 and the sheet metal hole, improving the deformation efficiency of the sheet metal 7, and reducing the risk of chip accumulation and sintering.

[0097] The concave arc 52 is suitable for connecting with the inscribed circle of the eccentric three-impeller structure; a front angle 521 is formed between the tangent of the concave arc 52 at the first end point 511 and the line connecting the first end point 511 and the center of the circumscribed circle. The front angle 521 is an acute angle. The sharp front angle 521 can provide sheet metal 7 deformation efficiency, reduce extrusion force, and reduce power consumption. Reasonable increase in the front angle 521 can reduce the extrusion deformation force and friction, and reduce the processing temperature. The concave arc 52 area can also accommodate debris, making the tapping process smoother, thereby reducing the roughness of the hole wall surface, improving the surface quality and subsequent thread quality. This structure has the function of trimming and cleaning the hole wall, preparing for subsequent tapping, and reducing the processing torque and air accuracy requirements.

[0098] In an exemplary embodiment, the convex arc 51 includes a first convex arc 516 and a second convex arc 517. The first convex arc 516 is provided with a first end point 511. The second convex arc 517 is connected to the first convex arc 516 and is provided with a second end point 512. A second clearance angle 515 is formed between the tangent line at the connection of the second convex arc 517 and the first convex arc 516 and the first tangent line 513, and the second clearance angle 515 is greater than the first clearance angle 514 (the second convex arc 517 is equivalent to a finishing arc design); the horizontal normal length of the first convex arc 516 is the blade width 518. Compared with the structure having only one convex arc 51, this structure can reduce the angle of the first clearance angle 514 and increase the blade width 518, thereby being beneficial to improving the strength at the tip of the structure and being more suitable for penetrating high-strength sheet metal 7 material.

[0099] Embodiment Two

[0100] A connecting component includes a sheet metal 7 and the above self-tapping fastener. The self-tapping fastener is in threaded fit with the sheet metal 7 and has the beneficial effects brought by the above self-tapping fastener.

[0101] Specifically, referring to Figures 12-14 、 Figure 2 , the sheet metal 7 is not initially provided with a sheet metal hole. During the self-tapping process of the self-tapping fastener, the tail 6 first contacts the sheet metal 7 and stretches the sheet metal 7 to form a convex bulge, preparing for subsequent further stretching and reaming. The guiding cone part 5 trims and cleans the hole wall, preparing for subsequent tapping. The rounding part 4 further performs secondary trimming on the hole wall completed by reaming through the guiding cone part 5 to stabilize the hole diameter size, preparing for subsequent threading. The threaded part 3 guides the thread to penetrate into the sheet metal hole to form a thread and is in threaded fit with the sheet metal hole. Finally, the supporting surface 211 contacts the sheet metal 7 to achieve self-tapping. To increase performances such as sealing, a gasket or the like can be installed on the sheet metal 7. At this time, the supporting surface 211 contacts the gasket (clamping part) to complete self-tapping.

[0102] The above description of the specification and embodiments is used to explain the protection scope of the present invention, but does not constitute a limitation on the protection scope of the present invention. Through the inspiration of the present invention or the above embodiments, those of ordinary skill in the art, in combination with common general knowledge, ordinary technical knowledge in the art and / or the prior art, through logical analysis, reasoning or limited experiments, can obtain modifications, equivalent replacements or other improvements to the embodiments of the present invention or some of its technical features, which should all be included within the protection scope of the present invention.

Claims

1. A self-tapping fastener, characterized in that: including a top-down connected driving part (1), flange part (2); thread part (3) which is provided with an external thread; a guiding cone part (5) which is in a frustum structure with its size gradually decreasing from top to bottom, and its horizontal cross-section is an eccentric three-impeller structure, the eccentric direction of the eccentric three-impeller structure is opposite to the spiral direction of the external thread; the eccentric three-impeller structure includes three convex arcs (51) and three concave arcs (52), and the convex arcs (51) connect two adjacent concave arcs (52); tail part (6) with its size gradually decreasing from top to bottom.

2. A self-tapping fastener according to claim 1, characterized in that: the outer wall of the driving part (1) is provided with a driving surface (111), the driving part (1) is further provided with a driving groove (121), and the notch of the driving groove (121) faces upward.

3. The self-tapping fastener according to claim 1, wherein: the flange part (2) includes a flange body (21) and a protrusion (22) protruding radially from the flange body (21) along the flange body (21), the flange body (21) is provided with a downward-facing supporting surface (211), and there is a gap between the bottom surface of the protrusion (22) and the supporting surface (211).

4. The self-tapping fastener according to claim 3, wherein: the bottom surface and / or the side wall of the protrusion (22) is provided with a lace (221).

5. The self-tapping fastener according to claim 1, wherein: the thread part (3) includes a first external thread (311), a second external thread (3211) and a third external thread (3221) arranged from top to bottom, the horizontal cross-section of the first external thread (311) is circular, both the second external thread (3211) and the third external thread (3221) are triangular rod threads, the outer diameter of the second external thread (3211) remains unchanged from top to bottom, and the outer diameter of the third external thread (3221) gradually decreases from top to bottom.

6. The self-tapping fastener according to claim 1, wherein: further including a rounding part (4), both ends of the rounding part (4) are respectively connected to the guiding cone part (5) and the thread part (3); the rounding part (4) is in a cylindrical structure, the outer wall of the rounding part (4) is a smooth surface, and its outer diameter remains unchanged from top to bottom.

7. The self-tapping fastener according to claim 1, characterized in that: the tail part (6) is in a triangular pyramid structure, the orthographic projection contour of the tail part (6) includes a horizontal line segment (61) and arcs (62) connected to both ends of the horizontal line segment (61), the distance between the two arcs (62) and the axis of the self-tapping fastener gradually decreases from top to bottom until the two arcs (62) are connected; the horizontal cross-section of the tail part (6) is circular or triangular, and the difference between the inscribed circle diameter and the circumscribed circle diameter of the horizontal cross-section of the tail part (6) is (0 - 0.5)P, where P is the thread pitch of the thread part (3).

8. The self-tapping fastener according to claim 1, characterized in that: The first end point (511) of the convex arc (51) starts from the circumcircle of the eccentric three - impeller structure, and the second end point (512) is located inside the circumcircle; the concave arc (52) is adapted to be in contact with the inscribed circle of the eccentric three - impeller structure. A first clearance angle (514) is formed between the tangent of the first end point (511) and the first tangent (513) of the circumcircle at the first end point (511); the tangent of the concave arc (52) at the first end point (511) and the connection line between the first end point (511) and the center of the circumcircle form a rake angle (521), and the rake angle (521) is an acute angle.

9. The self-tapping fastener according to claim 8, wherein: The convex arc (51) includes a first convex arc (516) and a second convex arc (517). The first convex arc (516) is provided with the first end point (511). The second convex arc (517) is connected to the first convex arc (516) and is provided with the second end point (512). A second clearance angle (515) is formed between the tangent at the connection of the second convex arc (517) and the first convex arc (516) and the first tangent (513), and the second clearance angle (515) is greater than the first clearance angle (514); the horizontal normal length of the first convex arc (516) is the blade width (518).

10. A connecting component, characterized in that: It includes a sheet metal (7) and a self - tapping fastener according to any one of claims 1 - 9, and the self - tapping fastener is in threaded fit with the sheet metal (7).

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