Connecting assembly

Abstract

The invention discloses a connecting assembly. The connecting assembly comprises an automatic fastening piece, a first plate, a foaming piece and a second plate, the self-tapping fastener comprises a driving part, a threaded part and a tail part which are sequentially connected in the first direction, the driving part is suitable for abutting against the surface, deviating from the second plate, of the first plate, and the tail part is suitable for stretching the second plate to form a via hole; the thread part is provided with an external thread, and the external thread is suitable for forming an internal thread on the via hole and is matched with a via hole thread in the second plate. In the self-tapping process, high temperature is generated, so that the foaming piece is heated and expanded to fill the gap between the self-tapping fastener and the via hole, and the shockproof and sealing effects are achieved.

Description

Technical Field

[0001] The present invention relates to the field of fasteners, and in particular to a connection assembly. Background Art

[0002] In the prior art, it is a common technique to make holes with self-tapping fasteners and to mate with the plate threads. However, sealing cannot be achieved at the threaded joints, and the self-tapping fasteners are prone to shaking relative to the plate because the joints are not tight. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects or problems in the background technology or provide a material basis for overcoming the above-mentioned defects or problems in the background technology, and to provide a connection component.

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

[0005] 1. Solution 1, a connection assembly comprising a self-tapping fastener and a first plate, a foamed member, and a second plate arranged in sequence along a first direction;

[0006] The self-tapping fastener comprises a driving portion, a threaded portion, and a tail portion connected in sequence along a first direction, wherein the driving portion is adapted to abut against a surface of the first plate facing away from the second plate, and the tail portion is adapted to stretch the second plate to form a through hole; the threaded portion is provided with an external thread, and the external thread cooperates with the through hole thread on the second plate.

[0007] The foaming member expands when heated to at least fill the gap between the self-tapping fastener and the through hole.

[0008] Solution 2: Based on Solution 1, the tail portion includes a smooth area and a tip area, the size of the smooth area along the first direction remains unchanged, and the size of the tip area along the first direction gradually decreases.

[0009] Option three, based on option two, a receiving groove suitable for accommodating grease or wax layer is provided on the tail, and the inclination direction of the receiving groove is opposite to the spiral direction of the external thread.

[0010] Solution 4: Based on Solution 3, the accommodating groove is a water drop groove, and the size of the accommodating groove gradually decreases along the first direction.

[0011] Option 5, based on Option 3, the accommodating groove extends from the smooth area to the tip area.

[0012] Option six, based on option two, the horizontal cross-sectional outer contours of the smooth area and the tip area are composed of four straight line segments and four arc segments, the two ends of each straight line segment are connected to two arc segments, and the arc segments are convex arcs.

[0013] Option seven, based on Option two, the tail also includes an expansion zone, the expansion zone is connected to the end of the stable zone away from the tip zone, and the outer diameter of the expansion zone is larger than the size of the stable zone.

[0014] Option 8, based on Option 1, the threaded portion includes a functional portion and an attacking portion arranged along a first direction, and the horizontal cross-sectional outer contour of the functional portion is circular; the horizontal cross-sectional outer contour of the attacking portion is composed of four first arc segments and four second arc segments, and the two ends of each first arc segment are connected to two second arc segments, the radius and arc length of the first arc segment are both greater than those of the second arc segment, and the distance from the second arc segment to the center axis of the self-tapping fastener is greater than the distance from the first arc segment to the center axis of the self-tapping fastener; the first arc segment and the second arc segment are convex arcs.

[0015] Option nine, based on option eight, the attacking part includes a finishing part and a guide part, the two ends of the finishing part are respectively connected to the functional part and the guide part, the outer diameter of the guide part gradually decreases along the first direction, and the outer diameter of the finishing part remains unchanged along the first direction.

[0016] Solution 10, based on Solution 8, a chip groove extending along the first direction is provided on the outer wall of the attacking portion.

[0017] From the above description of the present invention and its preferred embodiments, it can be seen that compared with the prior art, the technical solution of the present invention and its preferred embodiments have the following beneficial effects due to the adoption of the following technical means:

[0018] 1. Solution 1 and its preferred embodiment, a connection assembly comprising a self-tapping fastener and a first plate, a foamed member, and a second plate arranged in sequence along a first direction;

[0019] The self-tapping fastener comprises a driving portion, a threaded portion, and a tail portion, connected in sequence along a first direction. The driving portion is adapted to abut against the surface of the first plate facing away from the second plate, while the tail portion is adapted to stretch the second plate to form a via hole. The threaded portion has external threads adapted to form internal threads in the via hole and mate with the via threads on the second plate. The self-tapping process generates high temperatures, causing the foam to expand to at least fill the gap between the self-tapping fastener and the via hole, providing shock absorption and sealing.

[0020] 2. In the second solution and its preferred embodiment, the tail portion includes a smooth area and a tip area, and the size of the smooth area along the first direction remains unchanged so as to smooth the via hole.

[0021] The size of the tip area gradually decreases along the first direction, so as to facilitate gradual penetration into the sheet metal and facilitate hole making.

[0022] 3. In scheme three and its preferred embodiment, the tail penetrates into the sheet metal and squeezes the sheet metal material, generating a large amount of frictional heat during the stretching and hole-making process. The grease or wax layer pre-placed in the accommodating groove melts due to the heat, and the strong grease is impregnated on the tail and contacts the hole wall of the through hole, which can effectively prevent the workpiece from being scratched, scored, scratched, burst, sintered, and broken. The inclination direction of the accommodating groove is opposite to the spiral direction of the external thread to facilitate the downward discharge of grease.

[0023] 4. In the fourth solution and its preferred embodiment, the accommodating groove is a water drop groove, and the size of the accommodating groove gradually decreases along the first direction to facilitate the diversion of grease.

[0024] 5. In the fifth solution and its preferred embodiment, the receiving groove extends from the stable area to the tip area, thereby increasing the amount of wax or grease and the lubrication range, so that the entire hole making process is better protected.

[0025] 6. In Option 6 and its preferred embodiment, the horizontal cross-sectional profile of the plateau and tip regions is composed of a number of alternating straight and curved segments. Each straight segment is connected at both ends by two curved segments, each of which is convex. These segments form a sector-shaped surface on the axis rather than a ridgeline, increasing the contact area with the sheet metal and providing more initial deformation resistance and frictional heat, thereby facilitating the triggering of thermal expansion of the foaming material. Furthermore, as the sector-shaped surface increases in size from bottom to top, the frictional heat and sheet metal deformation generated during self-tapping also increase. However, the presence of the straight segments reduces the resistance and contact area with the sheet metal, ensuring that the contact between the tail and the sheet metal remains intermittent. Furthermore, compared to a fully circular surface, the sector-shaped surface ensures the force and energy required for downward compression and stretching of the sheet metal while preventing overheating, sintering, and cracking caused by excessive resistance. The straight segments are located inward of the curved segments, providing a clearance and chip containment function, reducing penetration torque and improving penetration stability.

[0026] 7. In Option 7 and its preferred embodiment, the tail also includes an expansion zone, which is connected to the end of the stable zone away from the tip zone. The outer diameter of the expansion zone is larger than the size of the stable zone, and is used to remove and squeeze debris and oil stains, ensure the smoothness of the hole wall and the stability of the friction coefficient, and ultimately ensure the stability of the tightening process.

[0027] 8. In the eighth embodiment and its preferred embodiment, the threaded portion includes a functional portion and a driving portion arranged along a first direction. The functional portion has a circular horizontal cross-sectional profile and is designed to be screwed into a threaded hole in a self-drilled second plate to engage with the second plate's threads. The driving portion comprises a plurality of alternating first and second arc segments, each first arc segment being connected to two second arc segments at both ends. The radius and arc length of the first arc segment are both greater than those of the second arc segment, and the distance from the second arc segment to the central axis of the self-drilling fastener is greater than the distance from the first arc segment to the central axis of the self-drilling fastener. The first and second arc segments are convex. When the thread is driven into the through hole after being stretched by the tail portion, the second arc segment with a smaller arc length and located on the outside first contacts the through hole wall, squeezing and deforming the hole wall. This design ensures that the driving process generates maximum stress at the deformed portion and minimizes driving torque, facilitating the driving process. The convex shape of the first arc segment with a longer arc length helps reduce driving torque while ensuring sufficient axial connection strength. This provides sufficient thread shear area after tightening, thereby enhancing the thread's shear resistance.

[0028] 9. In the ninth embodiment and its preferred embodiment, the insertion portion comprises a finishing portion and a guide portion. The finishing portion is connected to the functional portion and the guide portion at both ends. The outer diameter of the guide portion gradually decreases along a first direction. The guide portion serves to guide the insertion of the thread, ensuring a smooth insertion process and preventing excessive insertion that may cause shearing of the material or even failure to insert the thread. The outer diameter of the finishing portion remains unchanged along the first direction. The finishing portion serves to perform a final finishing operation on the threaded hole formed by extrusion with the guide portion, ensuring a proper connection between the external thread of the functional portion and the internal thread formed by self-tapping extrusion during the final tightening process.

[0029] 10. In Scheme 10 and its preferred embodiments, due to the friction between the internal and external threads during the striking process, a large amount of frictional heat-bonded metal debris is generated. Poor discharge of debris may cause sintering between the striking part and the plate. A chip groove extending along the first direction is provided on the outer wall of the striking part. This design can be used for scraping and accommodating chips to ensure the smooth progress of the striking process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a front view of the self-tapping fastener in Example 1;

[0032] Figure 2 for Figure 1 Schematic diagram of the middle BB section;

[0033] Figure 3 for Figure 1 Schematic diagram of the CC section;

[0034] Figure 4 is a horizontal cross-sectional view of the stable area in Example 1;

[0035] Figure 5 A bottom view of the tip area in Example 1;

[0036] Figure 6 This is a schematic diagram of the first plate, the foamed part, and the second plate before processing in Example 1;

[0037] Figure 7 This is a structural diagram of the connection component in Example 1.

[0038] Description of main reference numerals:

[0039] 1 Self-tapping fastener; 11 Driving portion; 12 Threaded portion; 121 Functional portion; 122 Tapering portion; 1221 First arc segment; 1222 Second arc segment; 1223 Trimming portion; 1224 Guide portion; 1225 Chip groove; 13 Tail portion; 131 Expansion zone; 132 Stable zone; 1321 Straight segment; 1322 Arc segment; 1323 Receiving groove; 133 Tip zone; 2 First plate; 21 Through hole; 3 Foaming member; 4 Second plate; 41 Through hole; 5 First direction; DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are 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 ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] In the claims, description and drawings of the present invention, unless otherwise clearly defined, the use of terms such as "first", "second" or "third" is for the purpose of distinguishing different objects rather than for describing a specific order.

[0042] In the claims, specification and the above-mentioned drawings of the present invention, unless otherwise expressly defined, directional words such as the terms "center", "transverse", "longitudinal", "horizontal", "vertical", "top", "bottom", "inside", "outside", "up", "down", "front", "back", "left", "right", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are 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 direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the specific scope of protection of the present invention.

[0043] In the claims, description and above-mentioned drawings of the present invention, unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" should be understood in a broad sense, that is, any connection method without displacement relationship and relative rotation relationship between the two parties, that is, including non-detachable fixed connection, detachable fixed connection, integral connection and fixed connection through other devices or elements.

[0044] In the claims, description and drawings of the present invention, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0045] Example 1:

[0046] refer to Figure 1-Figure 7 , a connection assembly, comprising a self-tapping fastener 1 and a first plate 2, a foaming member 3 and a second plate 4 arranged in sequence along a first direction 5;

[0047] refer to Figure 1 The self-tapping fastener 1 comprises a driving portion 11, a threaded portion 12 and a tail portion 13 connected in sequence along a first direction 5.

[0048] The tail portion 13 is suitable for stretching the second plate 4 to form the through hole 41 . Specifically, the tail portion 13 includes an expansion area 131 , a stable area 132 and a tip area 133 sequentially connected along the first direction 5 .

[0049] The size of the tip region 133 along the first direction 5 gradually decreases, and its width at the top is wide and its width at the bottom is narrow, so as to penetrate the sheet metal and facilitate downward extrusion and deformation of the sheet metal material. The size of the stable region 132 along the first direction 5 remains unchanged. The horizontal cross-sectional profile of the stable region 132 and the tip region 133 is composed of a plurality of alternately connected straight line segments 1321 and arc segments 1322, as shown in FIG. Figure 4 、 Figure 5The horizontal cross-sectional profile of the tip region 133 and the smooth region 132 consists of four straight segments 1321 and four arc segments 1322. Each straight segment 1321 is connected to two arc segments 1322 at both ends. Arc segments 1322 are convex arcs, and straight segments 1321 are located inside the circumscribed circle formed by these segments. The outer arc segments 1322, located away from the axis of the self-tapping fastener 1, contact the sheet metal with a smaller area, generating greater stress, thereby facilitating deformation and flow of the sheet metal material. The straight segments 1321 are located inside the arc segments 1322, providing a clearance and chip containment function, reducing driving torque and improving driving stability. A receiving groove 1323 suitable for accommodating grease or wax is provided on the tail portion 13, located on the straight segment 1321 of the smooth region 132. The inclination of the receiving groove 1323 is opposite to the spiral direction of the external thread. If the external thread is right-handed, the receiving groove 1323 is tilted to the left to facilitate downward drainage of grease. Preferably, the receiving groove 1323 is a water drop groove, the size of the receiving groove 1323 gradually decreases along the first direction 5 and extends from the stable area 132 to the tip area 133 .

[0050] refer to Figure 1 The expansion zone 131 is connected to one end of the stable zone 132 away from the tip zone 133. The outer diameter of the expansion zone 131 is larger than the size of the stable zone 132 and is generally cylindrical. The expansion zone 131 and the stable zone 132 have a curved surface transition.

[0051] The threaded portion 12 is provided with an external thread, which is threadedly engaged with the through hole 41 on the second plate 4 (in some embodiments, the external thread is also threadedly engaged with the first plate 2). Specifically, the threaded portion 12 includes a functional portion 121 and a punching portion 122 arranged along the first direction 5. The two ends of the functional portion 121 are respectively connected to the driving portion 11 and the punching portion 122. The functional portion 121 is a metric threaded rod, which is used to be screwed into the threaded hole on the self-drilled second plate 4 to threadably engage with the second plate 4. Figure 2 The outer contour of the horizontal cross section of the functional portion 121 is circular, that is, the outer contour of the horizontal cross section of the external thread at the functional portion 121 is circular.

[0052] refer to Figure 3 The horizontal cross-sectional outer contour of the attacking portion 122 is composed of a plurality of alternately connected first arc segments 1221 and second arc segments 1222. Specifically, the horizontal cross-sectional outer contour of the attacking portion 122 is composed of four first arc segments 1221 and four second arc segments 1222. The two ends of each first arc segment 1221 are connected to two second arc segments 1222. The distance from the second arc segment 1222 to the central axis of the self-tapping fastener 1 is greater than the distance from the first arc segment 1221 to the central axis of the self-tapping fastener 1. The radius and arc length of the first arc segment 1221 are both greater than those of the second arc segment 1222. The first arc segment 1221 and the second arc segment 1222 are both convex arcs.

[0053] Preferably, the attacking portion 122 includes a trimming portion 1223 and a guide portion 1224. The trimming portion 1223 is connected to the functional portion 121 and the guide portion 1224 at both ends. The outer diameter of the guide portion 1224 gradually decreases along the first direction 5, presenting an overall cross-sectional structure with a smaller bottom and a larger top. The outer diameter of the trimming portion 1223 remains constant along the first direction 5, and its upper and lower cross-sectional structures are identical. The outer wall of the attacking portion 122 is provided with a chip flute 1225 extending along the first direction 5. In this embodiment, the chip flute 1225 is distributed along the first arc segment 1221, and at least one chip flute is provided.

[0054] The driving portion 11 is adapted to abut against the surface of the first plate 2 facing away from the second plate 4 . The driving portion 11 may be of an external drive type, an internal drive type, or an internal and external dual drive type.

[0055] refer to Figure 6 Before self-tapping, the corresponding self-tapping position on the first plate 2 can be designed as a through hole 21 or a form without a hole. In this embodiment, there is a corresponding through hole 21, and the size of the through hole 21 can be equal to the thread diameter of the external thread.

[0056] Before self-tapping, the corresponding self-tapping portion on the foam member 3 can be designed as a through hole 21 or without a hole. In this embodiment, a through hole 21 is preferred. The foam member 3 can be made of a foam sealing material such as foamed silicone. When heated, the foam member 3 expands to fill the gap between the self-tapping fastener 1 and the through hole 41.

[0057] Before self-tapping, the corresponding self-tapping position on the second plate 4 is in the form of a non-hole, and a through hole 41 is formed under the action of the tail 13 of the self-tapping fastener 1, and an internal thread is formed under the action of the threaded portion 12.

[0058] When processing, refer to Figure 6 、 Figure 7 The foam member 3 is placed on the second plate 4, and the first plate 2 is placed on the foam member 3. If the first plate 2 and the foam member 3 have through holes 21, the through holes 21 of the two are arranged to correspond. The device drives the driving part 11 of the self-tapping fastener 1 to rotate at high speed and press downward.

[0059] The tip 133 of the tail 13 penetrates the second plate 4 and stretches downward, shaping the flange to pre-set the via 41. During this process, the grease in the accommodating groove 1323 melts and lubricates the area. Simultaneously, the foam 3 expands due to heat, filling the gap between the self-tapping fastener 1 and the via 41 and through-hole 21. The guide portion 1224 of the tapping portion 122 taps the via 41, creating an internal thread. The finishing portion 1223 further refines the internal thread. The functional portion 121 is screwed into the internal thread until the driving portion 11 of the self-tapping fastener 1 contacts the first plate 2, completing the fastening process.

[0060] Compared with the prior art, this embodiment has the following beneficial effects:

[0061] In an exemplary embodiment, a connection assembly includes a self-tapping fastener 1 and a first plate 2, a foamed part 3, and a second plate 4 arranged in sequence along a first direction 5;

[0062] The self-tapping fastener 1 comprises a driving portion 11, a threaded portion 12, and a tail portion 13, sequentially connected along a first direction 5. The driving portion 11 is adapted to abut against the surface of the first plate 2 facing away from the second plate 4, while the tail portion 13 is adapted to stretch the second plate 4 to form a through-hole 41. The threaded portion 12 has an external thread adapted to form an internal thread in the through-hole 41 and to threadably engage with the through-hole 41 in the second plate 4. During the self-tapping process, high temperatures are generated, causing the foam member 3 to expand to at least fill the gap between the self-tapping fastener 1 and the through-hole 41, thereby providing shock absorption and sealing.

[0063] In an exemplary embodiment, the tail portion 13 includes a stable area 132 and a tip area 133 . The stable area 132 has a constant size along the first direction 5 so as to smooth the via hole 41 .

[0064] The size of the tip area 133 along the first direction 5 gradually decreases, so as to facilitate gradual penetration into the sheet metal and facilitate hole making.

[0065] In an exemplary embodiment, the tail portion 13 penetrates into the sheet metal and squeezes the sheet metal material, generating a large amount of frictional heat during the stretching and hole-making process. The grease or wax layer pre-placed in the accommodating groove 1323 melts due to the heat, and the strong grease is impregnated on the tail portion 13 and contacts the hole wall of the through hole 41, which can effectively prevent the workpiece from being scratched, scored, scratched, burst, sintered, and ruptured. The inclination direction of the accommodating groove 1323 is opposite to the spiral direction of the external thread to facilitate the downward discharge of grease.

[0066] In an exemplary embodiment, the receiving groove 1323 is a water drop groove, and the size of the receiving groove 1323 gradually decreases along the first direction 5 to facilitate the diversion of grease.

[0067] In an exemplary embodiment, the receiving groove 1323 extends from the stable area 132 to the tip area 133, thereby increasing the amount of wax or grease and the lubrication range, thereby providing better protection for the entire hole making process.

[0068] In one exemplary embodiment, the horizontal cross-sectional profile of the plateau region 132 and the tip region 133 is composed of a plurality of alternating straight segments 1321 and arc segments 1322. Each straight segment 1321 is connected at both ends by two arc segments 1322. The arc segments 1322 are convex arcs, forming a sector-shaped surface on the axis rather than a ridgeline. This increases the contact area with the sheet metal, providing more initial deformation resistance and frictional heat, thereby facilitating the triggering of thermal expansion of the foaming material. Furthermore, as the sector-shaped surface increases in size from bottom to top, the frictional heat and sheet metal deformation generated during self-tapping also increase. However, the presence of the straight segments reduces the resistance and contact area with the sheet metal, ensuring that the contact between the tail portion 13 and the sheet metal remains intermittent. Furthermore, compared to a fully circular surface, the sector-shaped surface ensures the force and energy required for downward compression and stretching of the sheet metal while also preventing overheating, sintering, and cracking caused by excessive resistance. The straight line segment 1321 is located on the inner side relative to the arc segment 1322, and plays the role of avoiding and accommodating chips, thereby reducing the driving torque and improving the driving stability.

[0069] In an exemplary embodiment, the tail portion 13 also includes an expansion area 131, which is connected to the end of the smooth area 132 away from the tip area 133. The outer diameter of the expansion area 131 is larger than the size of the smooth area 132, and is used to remove and squeeze debris and oil stains, ensure the smoothness of the hole wall and the stability of the friction coefficient, and ultimately ensure the stability of the tightening process.

[0070] In an exemplary embodiment, the threaded portion 12 includes a functional portion 121 and a striking portion 122 arranged along the first direction 5. The horizontal cross-sectional outer contour of the functional portion 121 is circular, and is used to be screwed into the threaded hole on the self-drilled second plate 4 to cooperate with the thread of the second plate 4; the horizontal cross-sectional outer contour of the striking portion 122 is composed of a plurality of alternatingly connected first arc segments 1221 and second arc segments 1222, and each first arc segment 1221 is connected to two second arc segments 1222 at both ends. The radius and arc length of the first arc segment 1221 are both greater than those of the second arc segment 1222, and the distance from the second arc segment 1222 to the center axis of the self-drilling fastener 1 is greater than the distance from the first arc segment 1221 to the center axis of the self-drilling fastener 1; the first arc segment 1221 and the second arc segment 1222 are convex arcs. When the thread is driven into the through hole 41 after being stretched by the tail portion 13, the second arc segment 1222, with a smaller arc length and located on the outside, first contacts the wall of the through hole 41, squeezing and deforming the wall. This design ensures that the driving process generates maximum stress at the deformed area and minimizes driving torque, facilitating the driving process. The first arc segment 1221, with its longer arc length, is convex, which helps to reduce driving torque while ensuring sufficient axial connection strength. After tightening, it provides sufficient thread shear area and enhances the thread's shear resistance.

[0071] In one exemplary embodiment, the insertion portion 122 includes a finishing portion 1223 and a guide portion 1224. The finishing portion 1223 connects the functional portion 121 and the guide portion 1224 at either end. The outer diameter of the guide portion 1224 gradually decreases along the first direction 5. The guide portion 1224 guides the thread insertion, ensuring a smooth insertion process and preventing excessive insertion that could shear the material or even prevent insertion failure. The outer diameter of the finishing portion 1223 remains constant along the first direction 5. The finishing portion 1223 performs the final finishing of the threaded hole extruded by the guide portion 1224, ensuring a proper connection between the external thread of the functional portion 121 and the internal thread extruded by the self-tapping extrusion during the final tightening process.

[0072] In an exemplary embodiment, due to the friction between the internal and external threads during the striking process, a large amount of frictional heat-bonded metal debris is generated. Poor discharge of debris may cause sintering between the striking portion 122 and the plate. A chip groove 1225 extending along the first direction 5 is provided on the outer wall of the striking portion 122. This design can be used for scraping and accommodating chips to ensure the smooth progress of the striking process.

[0073] The above description and embodiments are intended to explain the scope of protection of the present invention, but do not constitute a limitation thereto. Modifications, equivalent substitutions, or other improvements to the embodiments of the present invention or portions thereof that can be obtained by a person of ordinary skill in the art through logical analysis, reasoning, or limited experimentation based on the teachings of the present invention or the above embodiments, combined with common knowledge, ordinary technical knowledge in the field, and / or prior art, should all be included within the scope of protection of the present invention.

Claims

1. A connection assembly, characterized in that: It comprises a self-tapping fastener (1) and a first plate (2), a foaming member (3) and a second plate (4) arranged in sequence along a first direction (5); The self-tapping fastener (1) comprises a driving portion (11), a threaded portion (12) and a tail portion (13) connected in sequence along a first direction (5); the driving portion (11) is adapted to abut against a surface of the first plate (2) facing away from the second plate (4); the tail portion (13) is adapted to stretch the second plate (4) to form a through hole (41); the threaded portion (12) is provided with an external thread, and the external thread is threadably engaged with the through hole (41) on the second plate (4); The foaming member (3) expands when heated so as to be suitable for at least filling the gap between the self-tapping fastener (1) and the through hole (41).

2. A connection assembly according to claim 1, characterized in that: The tail portion (13) comprises a stable area (132) and a tip area (133), wherein the size of the stable area (132) along the first direction (5) remains unchanged, and the size of the tip area (133) along the first direction (5) gradually decreases.

3. A connection assembly according to claim 2, characterized in that: The tail portion (13) is provided with a receiving groove (1323) suitable for receiving grease or a wax layer, and the inclination direction of the receiving groove (1323) is opposite to the spiral direction of the external thread.

4. A connection assembly according to claim 3, characterized in that: The accommodating groove (1323) is a water drop groove, and the size of the accommodating groove (1323) gradually decreases along the first direction (5).

5. A connection assembly according to claim 3, characterized in that: The accommodating groove (1323) extends from the stable area (132) to the tip area (133).

6. A connection assembly according to claim 2, characterized in that: The horizontal cross-sectional outer contours of the smooth area (132) and the tip area (133) are composed of a plurality of alternately connected straight line segments (1321) and arc segments (1322), wherein the two ends of each straight line segment (1321) are connected to two arc segments (1322), and the arc segments (1322) are convex arcs.

7. A connection assembly according to claim 2, characterized in that: The tail portion (13) further comprises an expansion zone (131), wherein the expansion zone (131) is connected to an end of the stable zone (132) away from the tip zone (133), and an outer diameter of the expansion zone (131) is larger than a size of the stable zone (132).

8. The connection assembly according to claim 1, wherein: The threaded portion (12) comprises a functional portion (121) and a punching portion (122) arranged along a first direction (5); the outer contour of the horizontal cross section of the functional portion (121) is circular; the outer contour of the horizontal cross section of the punching portion (122) is composed of a plurality of alternately connected first arc segments (1221) and second arc segments (1222); the two ends of each first arc segment (1221) are connected to two second arc segments (1222); the radius and arc length of the first arc segment (1221) are both greater than those of the second arc segment (1222); the distance from the second arc segment (1222) to the central axis of the self-tapping fastener (1) is greater than the distance from the first arc segment (1221) to the central axis of the self-tapping fastener (1); and the first arc segment (1221) and the second arc segment (1222) are convex arcs.

9. A connection assembly according to claim 8, characterized in that: The attacking portion (122) includes a trimming portion (1223) and a guide portion (1224). The two ends of the trimming portion (1223) are respectively connected to the functional portion (121) and the guide portion (1224). The outer diameter of the guide portion (1224) gradually decreases along the first direction (5), while the outer diameter of the trimming portion (1223) remains unchanged along the first direction (5).

10. The connection assembly according to claim 8, characterized in that: A chip groove (1225) extending along the first direction (5) is provided on the outer wall of the attacking portion (122).

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