Self-piercing riveting lower die and self-piercing riveting structure

Abstract

The invention provides a self-piercing riveting lower die and a self-piercing riveting structure, the self-piercing riveting lower die comprises a lower die main body and a first boss arranged on the upper end face of the lower die main body, a blanking channel penetrates through the two ends of the lower die main body, the blanking channel comprises an avoiding channel and a blanking channel, and the upper end opening of the avoiding channel is located on the upper end face of the first boss. In the riveting process, the first boss extrudes the to-be-riveted plate to enable the to-be-riveted plate to be subjected to plastic deformation, then the to-be-riveted plate flows in the direction of the avoiding channel, and finally the to-be-riveted plate and the rivet form an interlocking structure better under the guidance of the avoiding channel.

Description

Technical Field

[0001] The invention relates to the technical field of riveting, in particular to a self-piercing riveting lower die and a self-piercing riveting structure. Background Art

[0002] Regarding the FSPR plane self-piercing riveting technology, the research found that when the sheet material is pressed into the annular groove and undergoes large plastic deformation, the annular groove often cannot be filled, that is, the material flow is not sufficient, which leads to insufficient interlocking between the solid rivet and the connected material, affecting the quality of the riveted point. Especially for materials with low ductility, the connection quality of the node formed by the traditional mold is significantly reduced.

[0003] Authorization announcement number CN219766582U discloses a self-piercing riveting die and a self-piercing riveting device, which specifically discloses: a self-piercing riveting die, used for continuously processing a sheet to be riveted, the sheet to be riveted and the self-piercing riveting die move relative to each other along a first direction; characterized in that the self-piercing riveting die comprises: a riveting die base, the top surface of the riveting die base is recessed inwardly along the riveting direction to form a cavity, the sheet to be riveted is riveted in the cavity; and at least one wing portion, the wing portion extends outwardly from the riveting die base along the first direction; and the wing portion is coplanar with the top surface of the riveting die base.

[0004] The above patent document increases the stress area of ​​the plate to be riveted and reduces the pressure by making the wing contact with the plate to be riveted, thereby reducing the cracking of the plate to be riveted during the riveting process. This structure can solve the problem of easy cracking of the plate to be riveted in SPR riveting, but it cannot solve the problem of 1600MPa hot-formed steel, high-strength steel and cast aluminum with an elongation of less than 10% in FSPR riveting, that is, it cannot solve the problem of insufficient interlocking between the solid rivet and the connected material, which affects the quality of riveting. Summary of the invention

[0005] In view of the problems existing in the above prior art, the purpose of the present invention is to provide a self-piercing riveting lower die and a self-piercing riveting structure, which can improve the interlocking effect between the rivet and the linked materials, especially, significantly improve the riveting quality of low ductility materials.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A self-piercing riveting lower die comprises a lower die body, a first boss is arranged on the upper end surface of the lower die body, a blanking channel runs through both ends of the lower die body, and when observed in a direction perpendicular to the upper end surface of the lower die body, the projection of the blanking channel is located inside the projection of the first boss; the blanking channel comprises an avoidance channel and a blanking channel, the upper port of the avoidance channel is located on the upper end surface of the first boss, the lower end of the avoidance channel is connected with the upper end of the blanking channel, and the cross-sectional dimension of the upper end of the avoidance channel is larger than the cross-sectional dimension of the upper end of the blanking channel.

[0008] Further, the avoidance channel includes a first sub-avoidance channel, an upper port of the first sub-avoidance channel is located on the upper end surface of the first boss, a lower end of the first sub-avoidance channel is connected to the upper end of the discharge channel, and a cross-sectional dimension of the upper end of the first sub-avoidance channel is larger than a cross-sectional dimension of the upper end of the discharge channel.

[0009] Furthermore, on a mid-section passing through the central axis of the lower mold body, the upper end of the first inner wall cut edge of the first sub-avoidance channel is connected to the upper end surface of the first boss, and the lower end of the first inner wall cut edge is connected to the inner wall of the blanking channel.

[0010] Further, on the mid-section, the first inner wall cut edge is a first straight line, or the first inner wall cut edge is a first curve.

[0011] Furthermore, the first inner wall cut edge is a first straight line, and the first inner wall cut edge forms a first angle with a first horizontal plane perpendicular to the central axis of the lower mold body.

[0012] Furthermore, the first angle ranges from 100° to 160°.

[0013] Further, the first inner wall cut edge is concave in a direction away from the central axis of the lower mold body and is curved; or the first inner wall cut edge is convex in a direction close to the central axis of the lower mold body and is curved; or the first inner wall cut edge is concave-convex.

[0014] Further, the avoidance channel includes a second sub-avoidance channel, the upper end of the second sub-avoidance channel is connected to the lower end of the first sub-avoidance channel, the lower end of the second sub-avoidance channel is connected to the upper end of the discharge channel, the cross-sectional dimension of the lower end of the first sub-avoidance channel is larger than the cross-sectional dimension of the upper end of the second sub-avoidance channel, and the cross-sectional dimension of the upper end of the second sub-avoidance channel is larger than the cross-sectional dimension of the upper end of the discharge channel.

[0015] Furthermore, on the mid-section passing through the central axis of the lower mold body, the upper end of the second inner wall cut edge of the second sub-avoidance channel is connected to the lower end of the first inner wall cut edge of the first sub-avoidance channel, and the lower end of the second inner wall cut edge is connected to the inner wall of the discharge channel.

[0016] Further, on the mid-section, the second inner wall cut edge is a second straight line, or the second inner wall cut edge is a second curve.

[0017] Furthermore, the first inner wall cut edge is a first straight line, and the first inner wall cut edge forms a second angle with a first horizontal plane perpendicular to the central axis of the lower mold body, and the second angle is greater than or equal to 90° and less than or equal to 160°.

[0018] Furthermore, the second inner wall cut edge is a second straight line, and the second inner wall cut edge forms a third angle with a second horizontal plane perpendicular to the central axis of the lower mold body.

[0019] Furthermore, the third angle is greater than 90° and less than or equal to 160°.

[0020] Furthermore, the second inner wall cut edge is concave and curved in a direction away from the central axis of the lower mold body; or the second inner wall cut edge is convex and curved in a direction close to the central axis of the lower mold body; or the second inner wall cut edge is concave-convex.

[0021] Further, the avoidance channel includes a third sub-avoidance channel, the upper end of the third sub-avoidance channel is connected to the lower end of the second sub-avoidance channel, the lower end of the third sub-avoidance channel is connected to the upper end of the discharge channel, the cross-sectional dimension of the lower end of the second sub-avoidance channel is larger than the cross-sectional dimension of the upper end of the third sub-avoidance channel, and the cross-sectional dimension of the upper end of the third sub-avoidance channel is larger than the cross-sectional dimension of the upper end of the discharge channel.

[0022] Furthermore, on the mid-section passing through the central axis of the lower mold body, the upper end of the third inner wall cut edge of the third sub-avoidance channel is connected to the lower end of the second inner wall cut edge of the second sub-avoidance channel, and the lower end of the third inner wall cut edge is connected to the inner wall of the discharge channel.

[0023] Further, on the mid-section, the third inner wall cut edge is a third straight line, or the third inner wall cut edge is a third curve.

[0024] Furthermore, the first inner wall cut edge is a first straight line, and the first inner wall cut edge forms a fourth angle with a first horizontal plane perpendicular to the central axis of the lower mold body, and the fourth angle is greater than 90° and less than or equal to 160°.

[0025] Furthermore, the second inner wall cut edge is a second straight line, and the second inner wall cut edge forms a fifth angle with a second horizontal plane perpendicular to the central axis of the lower mold body, and the fifth angle is greater than or equal to 90° and less than or equal to 160°.

[0026] Furthermore, the third inner wall cut edge is a third straight line, and the third inner wall cut edge forms a sixth angle with a third horizontal plane perpendicular to the central axis of the lower mold body, and the sixth angle is greater than 90° and less than or equal to 160°.

[0027] Furthermore, the third inner wall cut edge is concave in a direction away from the central axis of the lower mold body and is curved; or the third inner wall cut edge is convex in a direction close to the central axis of the lower mold body and is curved; or the third inner wall cut edge is concave-convex.

[0028] Furthermore, an outer wall of the first boss and a top surface of the lower mold body have a seventh angle.

[0029] Furthermore, the seventh angle ranges from 100° to 160°.

[0030] Furthermore, the upper end surface of the first boss is in a circular ring shape, and there is a first distance between the inner ring and the outer ring of the upper end surface of the first boss, and the first distance is at least 4-6 times the height of the first boss.

[0031] A self-piercing riveting structure comprises the self-piercing riveting lower die and an upper die body, a material feeding channel runs through both ends of the upper die body, and the material feeding channel overlaps with the blanking channel of the lower die body on the same vertical plane.

[0032] Furthermore, the lower end surface of the upper mold body is a plane, and the lower port of the material delivery channel is located on the lower end surface of the upper mold body.

[0033] Furthermore, a second boss is provided on the lower end surface of the upper mold body, the material conveying channel includes an avoidance channel and a feeding channel, the lower port of the avoidance channel is located on the lower end surface of the second boss, and the upper end of the avoidance channel is connected to the lower end of the feeding channel.

[0034] A self-piercing riveting structure, comprising the above-mentioned self-piercing riveting lower die and upper die main body, a material feeding channel runs through both ends of the upper die main body, and the material feeding channel and the blanking channel partially overlap on the same vertical plane; a second boss is arranged on the lower end surface of the upper die main body, when observed in the direction perpendicular to the lower end surface of the upper die main body, the material feeding channel is located inside the second boss; the material feeding channel comprises an avoidance channel and a feeding channel, the lower end of the avoidance channel is located on the lower end surface of the second boss, the upper end of the avoidance channel overlaps with the lower end of the feeding channel The two ends are connected, a punch is movably arranged in the feed channel; a rivet, the rivet is movably arranged in the feed channel; during riveting, the first boss and the second boss cooperate to press the sheet material to be riveted, the punch pushes the rivet out of the feed channel, and embeds the rivet into the sheet material to be riveted, the upper die body is pressed downward, the second boss squeezes the upper end of the sheet material to be riveted, the first boss squeezes the lower end of the sheet material to be riveted, the sheet material to be riveted moves toward the avoidance channel, and fills the recessed portion on the side of the rivet.

[0035] Furthermore, the rivet further comprises an upper pushing portion and a lower piercing portion, and two ends of the recessed portion are respectively connected to the upper pushing portion and the upper piercing portion.

[0036] Furthermore, the following formula is included:

[0037]

[0038] Among them, R is the radius of the recessed portion, h1 is the thickness of the upper pushing portion, h2 is the thickness of the lower puncture portion, h3 is the total thickness of the entire rivet, h4 is the height of the second boss, h is the height of the first boss, d4 is the outer diameter of the second boss, d5 is the inner diameter of the second boss, D1 is the first spacing between the inner ring and the outer ring of the upper end face of the first boss, α is the first angle, and β is the seventh angle.

[0039] The beneficial effects of the present invention are:

[0040] During riveting, the first boss continuously squeezes the sheet material to be riveted, causing the sheet material to be plastically deformed and flow toward the avoidance channel. Subsequently, under the guidance of the avoidance channel, the sheet material to be riveted completely fills the recessed portion on the side of the rivet, thereby improving the interlocking effect between the rivet and the sheet material to be riveted. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the planar structure of the self-piercing riveting structure of the present invention;

[0042] Figure 2 yes Figure 1A schematic diagram of the three-dimensional structure of the first embodiment of the self-piercing riveting lower die;

[0043] Figure 3 yes Figure 2 A top view schematic diagram of

[0044] Figure 4 yes Figure 2 A schematic cross-sectional view at A-A';

[0045] Figure 5 yes Figure 4 A schematic diagram of the structure at Z;

[0046] Figure 6 yes Figure 4 Schematic diagram of stress distribution of the sheet to be riveted during the riveting process by the self-piercing riveting lower die;

[0047] Figure 7 yes Figure 1 Schematic diagram of the three-dimensional structure of the self-piercing riveting upper die;

[0048] Figure 8 yes Figure 6 A schematic cross-sectional view at A-A';

[0049] Fig. 9 yes Figure 1 Schematic diagram of the plane structure of the middle rivet;

[0050] Fig.10 yes Figure 1 A schematic cross-sectional view of a second embodiment of a lower die for self-piercing riveting;

[0051] Fig.11 yes Figure 1 A schematic cross-sectional view of a third embodiment of a self-piercing riveting lower die;

[0052] Fig.12 yes Fig.11 Schematic diagram of stress distribution of the sheet to be riveted during the riveting process by the self-piercing riveting lower die;

[0053] Fig.13 yes Figure 1 A schematic cross-sectional view of a fourth embodiment of a self-piercing riveting lower die;

[0054] Fig.14 yes Figure 1 A schematic cross-sectional view of a fifth embodiment of a self-piercing riveting lower die;

[0055] Fig.15 yes Fig.12 A schematic diagram of the structure at Y;

[0056] Fig.16 yes Figure 1A schematic cross-sectional view of a sixth embodiment of a self-piercing riveting lower die;

[0057] Fig.17 yes Figure 1 A schematic cross-sectional view of a seventh embodiment of a self-piercing riveting lower die;

[0058] Fig.18 yes Figure 1 A schematic cross-sectional view of an eighth embodiment of a self-piercing riveting lower die;

[0059] Fig.19 yes Figure 1 A schematic cross-sectional view of a ninth embodiment of a self-piercing riveting lower die;

[0060] Fig. 20 yes Fig.17 A schematic diagram of the structure enlarged at X;

[0061] Fig.21 yes Figure 1 A cross-sectional schematic diagram of a tenth embodiment of a self-piercing riveting lower die;

[0062] Fig. 22 yes Figure 1 A cross-sectional schematic diagram of an eleventh embodiment of a self-piercing riveting lower die;

[0063] Fig.23 yes Figure 1 A schematic cross-sectional view of a twelfth embodiment of a self-piercing riveting lower die;

[0064] Fig.24 yes Figure 1 A schematic diagram of the planar structure of another embodiment of the middle upper mold body;

[0065] Fig.25 yes Fig. 22 A schematic cross-sectional view at A-A';

[0066] Fig.26 yes Fig.23 Enlarged schematic diagram of the structure at W.

[0067] Reference numerals

[0068] 1. Self-piercing riveting structure;

[0069] 2. Self-piercing riveting lower die; 21. Lower die body; 22. First boss; 221. Inner ring; 222. Outer ring; 23. Blanking channel; 231. Avoidance channel; 2311. First sub-avoidance channel; 23111. First inner wall cut edge; 2312. Second sub-avoidance channel; 23121. Second inner wall cut edge; 2313. Third sub-avoidance channel; 23131. Third inner wall cut edge; 232. Blanking channel; 24. Transition part;

[0070] 3. Upper mold; 31. Upper mold body; 32. Material feeding channel; 321. Avoidance channel; 322. Material feeding channel; 33. Second boss;

[0071] 4. Sheet materials to be riveted;

[0072] 5. Punch;

[0073] 6. Rivet; 61. Upper pushing portion; 62. Recessed portion; 63. Lower piercing portion. DETAILED DESCRIPTION

[0074] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "top surface", "bottom surface" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred position or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0075] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the definition of "first" and "second" features can explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0076] In the present invention, unless otherwise specified and limited, the terms "assemble", "connect", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection; it can be directly connected, or it can be connected through an intermediate medium, or the two elements can be internally connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. The following description is only exemplary and does not limit the protection scope of the present invention.

[0078] Please refer to Figure 1-Figure 26The present invention provides a self-piercing riveting structure 1, comprising a self-piercing riveting lower die 2, the self-piercing riveting lower die 2 comprising a lower die body 21, a first boss 22 is arranged on the upper end surface of the lower die body 21, a blanking channel 23 runs through both ends of the lower die body 21, and when viewed in a direction perpendicular to the upper end surface of the lower die body 21, the projection of the blanking channel 23 is located inside the projection of the first boss 22. The blanking channel 23 comprises an avoidance channel 231 and a blanking channel 232, the upper end of the avoidance channel 231 is located on the upper end surface of the first boss 22, the lower end of the avoidance channel 231 is connected to the upper end of the blanking channel 232, and the cross-sectional dimension of the upper end of the avoidance channel 231 is larger than the cross-sectional dimension of the upper end of the blanking channel 232.

[0079] Please refer to Figure 4-Figure 5 In this embodiment, the avoidance channel 231 includes a first sub-avoidance channel 2311, and the upper port of the first sub-avoidance channel 2311 is located on the upper end surface of the first boss 22. Preferably, a transition portion 24 is provided between the upper port of the first sub-avoidance channel 2311 and the upper end surface of the first boss 22, and the transition portion 24 can smoothly connect the upper end of the first sub-avoidance channel 2311 with the upper end surface of the first boss 22. The lower end of the first sub-avoidance channel 2311 is connected to the upper end of the unloading channel 232, and the cross-sectional dimension of the upper end of the first sub-avoidance channel 2311 is larger than the cross-sectional dimension of the upper end of the unloading channel 232, which is equivalent to the first sub-avoidance channel 2311 being a funnel-shaped structure that gradually gathers toward the middle from top to bottom.

[0080] Specifically, a middle section A-A' is provided through the center axis L1 of the lower mold body 21 and along the direction of the center axis L1 of the lower mold body 21, and the projection of the inner wall of the first sub-avoidance channel 2311 on the middle section A-A' is recorded as the first inner wall section 23111. In this embodiment, the first inner wall section 23111 is a first straight line, and the upper end of the first inner wall section 23111 is connected to the upper end surface of the first boss 22 through the aforementioned transition portion 24, and the lower end of the first inner wall section 23111 is connected to the inner wall of the discharge channel 232.

[0081] It should be noted that the length of the first inner wall cut edge 23111 is not limited in the present invention, and a specific value is selected according to actual working conditions.

[0082] Please refer to Figure 5In this embodiment, a first horizontal plane a passes through the first inner wall cut edge 23111 and is perpendicular to the aforementioned mid-section A-A'. A first angle A1 is formed between the first inner wall cut edge 23111 and the first horizontal plane a. The range of the first angle A1 is between 100° and 160°. Specifically, the purpose of setting the first angle A1 between the first inner wall cut edge 23111 and the first horizontal plane a is to guide the flow trend (direction) of the riveted sheet 4. Therefore, the specific value of the first angle A1 is not limited here and is selected within the aforementioned range according to actual needs.

[0083] In this embodiment, when viewed in a direction perpendicular to the upper end surface of the first boss 22, the upper end surface of the first boss 22 is annular. The inner ring 221 of the upper end surface of the first boss 22 is connected to the first inner wall cut edge 23111 through the transition portion 24, and the outer ring 222 of the upper end surface of the first boss 22 is connected to the top surface of the lower mold body 21 through the outer wall of the first boss 22. The design of the first boss 22 can reduce the stress concentration problem during the riveting process, thereby reducing the risk of cracks in the sheet material 4 to be riveted.

[0084] For details, please refer to Figure 4-Figure 5 , on the projection of the first boss 22 on the mid-section A-A', there is a seventh angle A7 between the outer wall of the first boss 22 and the upper end surface of the lower die body 21, and the range of the seventh angle A7 is between 100°-160°. When the contact position of the outer wall of the first boss 22 and the upper end surface of the lower die body 21 remains unchanged, the smaller the angle of the seventh angle A7, the larger the contact area between the first boss 22 and the sheet material 4 to be riveted, and the shear strength and overall stability during riveting will increase, thereby enhancing the firmness of the connection. On the other hand, this structural change of the first boss 22 gradually converging from the lower end to the upper end can further guide the flow trend (direction) of the sheet material 4 to be riveted in combination with the first inner wall cut edge 23111. Of course, since it is impossible to determine the working conditions during actual riveting, the specific angle of the seventh angle A7 is not limited here, and is selected within the aforementioned range according to actual needs.

[0085] More specifically, please refer to Figure 3 , there is a first spacing L2 between the inner ring 221 and the outer ring 222 on the upper end surface of the first boss 22, and the first spacing L2 is at least 4-6 times the height of the first boss 22. The larger the first spacing L2, the larger the contact area between the first boss 22 and the sheet material 4 to be riveted, and the shear strength and overall stability during riveting will increase. The specific length of the first spacing L2 is not limited here and is selected according to actual working conditions.

[0086] Please refer to Figure 1 , Figure 7 and Figure 8The self-piercing riveting structure 1 further includes an upper die 3, which includes an upper die body 31, the lower end surface of which is arranged opposite to the upper end surface of the lower die body 21 (also equivalent to the upper end surface of the first boss 22). A material feeding channel 32 runs through the upper and lower ends of the upper die body 31, and the material feeding channel 32 overlaps with the blanking channel 23 of the lower die body 21 on the same vertical plane (it can also be said that the upper die body 31 and the lower die body 21 are arranged on the same central axis L1).

[0087] In this embodiment, the lower end surface of the upper die body 31 is a plane, the lower end of the material delivery channel 32 is located on the lower end surface, and the size of the lower end of the material delivery channel 32 is substantially consistent with the size of the upper end of the avoidance channel 231. A punch 5 is provided in the material delivery channel 32, and the punch 5 can make a reciprocating motion in the material delivery channel 32.

[0088] Please refer to Figure 1 and Fig. 9 In this embodiment, a rivet 6 is also included. The rivet 6 is initially set in the feeding channel 32, and the punch 5 can push the rivet 6 to move in the feeding channel 32.

[0089] Specifically, the rivet 6 includes an upper push portion 61, a recessed portion 62 and a lower piercing portion 63, and the two ends of the recessed portion 62 are respectively connected to the upper push portion 61 and the lower piercing portion 63. The cross-sectional area of ​​the rivet 6 increases from the recessed portion 62 to the upper push portion 61 and the lower piercing portion 63. Combined with the structural characteristics of the first angle A1 of the first inner wall cut edge 23111, the first inner wall cut edge 23111 can face the recessed portion 62 of the rivet 6, and can guide the sheet material 4 to be riveted to flow in the direction of the recessed portion 62 during riveting.

[0090] In the FSPR self-piercing riveting process, when the rivet 6 is embedded in the sheet material 4 to be riveted and the first boss 22 squeezes the sheet material 4 to be riveted, stress concentration will occur at the connection between the sheet material 4 to be riveted and the rivet 6, resulting in cracks. The larger the value of the equivalent strain point, the easier it is for the sheet material 4 to be riveted to crack. At this time, the first inner wall cut edge 23111 (i.e., the first sub-avoidance channel 2311) can disperse the stress of the sheet material 4 to be riveted, thereby reducing the value of the equivalent strain point of the sheet material 4 to be riveted. Please refer to Figure 6 It can be seen that the maximum value of the equivalent strain point of the sheet material 4 to be riveted is less than 2 at this time, while when there is no first inner wall cut edge 23111 (i.e., the first sub-avoidance channel 2311) (equivalent to the first boss 22 directly squeezing the sheet material 4 to be riveted), the maximum value of the equivalent strain point of the sheet material 4 to be riveted is at least 3. Therefore, the existence of the first inner wall cut edge 23111 can effectively reduce the occurrence of cracks at the connection between the sheet material to be riveted and the rivet 6.

[0091] The working principle of the present invention is described below to better understand the present invention:

[0092] The sheet material 4 to be riveted is placed between the upper die body 31 and the lower die body 21, and the upper die body 31 is pressed down and cooperates with the lower die body 21 to pre-press the sheet material 4 to be riveted. The punch 5 is pressed down to push the rivet 6 out of the feeding channel 32, and the rivet 6 is embedded in the sheet material 4 to be riveted, and the material of the riveted part of the sheet material 4 to be riveted will be punched out and finally discharged from the lower die body 21 through the discharge channel 232. Then the upper die body 31 continues to press down, and the first boss 22 squeezes the lower end of the sheet material 4 to be riveted, so that the sheet material 4 to be riveted undergoes plastic deformation and flows in the direction of the avoidance channel 231, and under the guidance of the first inner wall cut edge 23111 of the avoidance channel 231, the recessed portion 62 of the rivet 6 is gradually filled, thereby better improving the interlocking effect between the rivet 6 and the sheet material 4 to be riveted.

[0093] The present invention has a blanking channel 23 that runs through both ends of the lower die body 21, and the blanking channel 23 includes an avoidance channel 231 and a blanking channel 232 that are connected in sequence, wherein the cross-sectional dimension of the upper end of the avoidance channel 231 is larger than the cross-sectional dimension of the upper end of the blanking channel 232, and the upper end of the avoidance channel 231 is arranged on the upper end surface of the first boss 22. Therefore, during riveting, the first boss 22 can squeeze the sheet material 4 to be riveted, so that after the sheet material 4 to be riveted undergoes plastic deformation, the recessed portion 62 of the rivet 6 can be fully filled under the guidance of the avoidance channel 231, so that the sheet material 4 to be riveted and the rivet 6 form an interlocking structure better.

[0094] Please refer to Fig.10 The self-piercing riveting lower die of the present invention also includes a second embodiment. The difference between the second embodiment and the first embodiment is that the structure of the first inner wall cut edge 23111 is changed, specifically:

[0095] In this embodiment, the first inner wall cut edge 23111 is in a first curved shape. The first inner wall cut edge 23111 is convex toward the direction close to the central axis L1 of the lower mold body 21 and is in a curved shape.

[0096] Other technical features and technical effects are consistent with those of the first embodiment and will not be elaborated here.

[0097] Please refer to Figure 11-12 The self-piercing riveting lower die of the present invention also includes a third embodiment. The difference between the third embodiment and the second embodiment is that the structure of the first inner wall cut edge 23111 is changed, specifically:

[0098] In this embodiment, the first inner wall cut edge 23111 is concave and curved in a direction away from the central axis L1 of the lower mold body 21. At this time, the maximum value of the equivalent strain point of the riveted sheet 4 is less than 2, and the riveted sheet 4 is not prone to cracks.

[0099] Other technical features and technical effects are consistent with those of the second embodiment and will not be elaborated here.

[0100] Please refer to Fig.13 The self-piercing riveting lower die of the present invention also includes a fourth embodiment. The difference between the fourth embodiment and the second embodiment is that the structure of the first inner wall cut edge 23111 is changed, specifically:

[0101] In this embodiment, the first inner wall cut edge 23111 can be bent into a concave-convex shape in a direction away from or close to the central axis L1 of the lower mold body 21 .

[0102] Other technical features and technical effects are consistent with those of the second embodiment and will not be elaborated here.

[0103] Please refer to Figure 14-15 The self-piercing riveting lower die of the present invention also includes a fifth embodiment. The difference between the fifth embodiment and the first embodiment is that the structure of the avoidance channel 231 is changed, specifically:

[0104] In this embodiment, the avoidance channel 231 also includes a second sub-avoidance channel 2312, which is located below the first sub-avoidance channel 2311, and the upper end of the second sub-avoidance channel 2312 is connected to the lower end of the first sub-avoidance channel 2311, and the lower end of the second sub-avoidance channel 2312 is connected to the upper end of the discharge channel 232.

[0105] Specifically, the cross-sectional dimension of the lower end of the first sub-avoidance channel 2311 is larger than the cross-sectional dimension of the upper end of the second sub-avoidance channel 2312, and the cross-sectional dimension of the upper end of the second sub-avoidance channel 2312 is larger than the cross-sectional dimension of the upper end of the material discharge channel 232. It is equivalent to the first sub-avoidance channel 2311 combined with the second sub-avoidance channel 2312, and the whole presents a structure that gradually converges toward the central axis L1 from the upper end to the lower end.

[0106] In this embodiment, according to the projection of the lower mold body 21 on the mid-section A-A', the projection of the inner wall of the second sub-avoidance channel 2312 on the mid-section A-A' is recorded as the second inner wall section 23121, the second inner wall section 23121 is a second straight line, the upper end of the second inner wall section 23121 is connected to the lower end of the first inner wall section 23111 of the first sub-avoidance channel 2311, and the lower end of the second inner wall section 23121 is connected to the inner wall of the discharge channel 232.

[0107] It should be noted that the length of the second inner wall cut edge 23121 is not limited in the present invention, and a specific value is selected according to actual working conditions.

[0108] Specifically, the first inner wall cut edge 23111 is a first straight line, and there is a second angle A2 between the first inner wall cut edge 23111 and the first horizontal plane a (it should be noted that the first angle A1 and the second angle A2 are both the angles between the first inner wall cut edge 23111 and the first horizontal plane a, and the first angle A1 and the second angle A2 are used here to facilitate distinction in different embodiments). The range of the second angle A2 is between 90° and 160°. The specific value of the second angle A2 is not limited here, and is selected within the aforementioned range according to actual working conditions.

[0109] More specifically, a second horizontal plane b passes through the second inner wall cut edge 23121 and is perpendicular to the mid-section A-A', and a third angle A3 is formed between the second inner wall cut edge 23121 and the second horizontal plane b, and the third angle A3 is greater than 90° and less than or equal to 160°. The specific value of the third angle A3 is not limited here, and is selected within the aforementioned range according to actual working conditions.

[0110] Other technical features and technical effects are consistent with those of the first embodiment and will not be elaborated here.

[0111] Please refer to Fig.16 The self-piercing riveting lower die of the present invention also includes a sixth embodiment. The difference between the sixth embodiment and the fifth embodiment is that the structure of the second inner wall cut edge 23121 is changed, specifically:

[0112] In this embodiment, the second inner wall cut edge 23121 is in a second curved shape. The second inner wall cut edge 23121 is convex toward the direction close to the central axis L1 of the lower mold body 21 and is in a curved shape.

[0113] Other technical features and technical effects are consistent with those of the fifth embodiment and will not be elaborated here.

[0114] Please refer to Fig.17 The self-piercing riveting lower die of the present invention also includes a seventh embodiment. The difference between the seventh embodiment and the sixth embodiment is that the structure of the second inner wall cut edge 23121 is changed, specifically:

[0115] In this embodiment, the second inner wall cut edge 23121 is concave and curved in a direction away from the central axis L1 of the lower mold body 21 .

[0116] Other technical features and technical effects are consistent with those of the sixth embodiment and will not be elaborated here.

[0117] Please refer to Fig.18 The self-piercing riveting lower die of the present invention also includes an eighth embodiment. The difference between the eighth embodiment and the sixth embodiment is that the structure of the second inner wall cut edge 23121 is changed, specifically:

[0118] The second inner wall cut edge 23121 may be bent into a concave-convex shape in a direction away from or close to the central axis L1 of the lower mold body 21 .

[0119] Other technical features and technical effects are consistent with those of the sixth embodiment and will not be elaborated here.

[0120] Please refer to Figure 19-20 The self-piercing riveting lower die of the present invention also includes a ninth embodiment. The difference between the ninth embodiment and the fifth embodiment is that the structure of the avoidance channel 231 is changed, specifically:

[0121] In this embodiment, the avoidance channel 231 also includes a third sub-avoidance channel 2313, which is located below the second sub-avoidance channel 2312, the upper end of the third sub-avoidance channel 2313 is connected to the lower end of the second sub-avoidance channel 2312, and the lower end of the third sub-avoidance channel 2313 is connected to the upper end of the discharge channel 232.

[0122] Specifically, the cross-sectional dimension of the lower end of the second sub-avoidance channel 2312 is greater than the cross-sectional dimension of the upper end of the third sub-avoidance channel 2313, and the cross-sectional dimension of the upper end of the third sub-avoidance channel 2313 is greater than the cross-sectional dimension of the upper end of the material discharge channel 232. This is equivalent to the first sub-avoidance channel 2311, the second sub-avoidance channel 2312 combined with the third sub-avoidance channel 2313, which as a whole presents a structure that gradually converges toward the central axis L1 from the upper end to the lower end.

[0123] In this embodiment, according to the projection of the lower mold body 21 on the mid-section A-A', the projection of the inner wall of the third sub-avoidance channel 2313 on the mid-section A-A' is recorded as the third inner wall section 23131, and the third inner wall section 23131 is a third straight line. The upper end of the third inner wall section 23131 is connected to the lower end of the second inner wall section 23121 of the second sub-avoidance channel 2312, and the lower end of the third inner wall section 23131 is connected to the inner wall of the discharge channel 232.

[0124] It should be noted that the length of the third inner wall cut edge 23131 is not limited in the present invention, and a specific value is selected according to actual working conditions.

[0125] Specifically, the first inner wall cut edge 23111 is a first straight line, and there is a fourth angle A4 between the first inner wall cut edge 23111 and the first horizontal plane a (it should be noted that the first angle A1, the second angle A2 and the fourth angle A4 are all angles between the first inner wall cut edge 23111 and the first horizontal plane a, and the first angle A1, the second angle A2 and the fourth angle A4 are used here to facilitate distinction in different embodiments). The fourth angle A4 is greater than 90° and less than or equal to 160°. The specific value of the fourth angle A4 is not limited here, and is selected within the aforementioned range according to actual working conditions.

[0126] Further, the second inner wall cut edge 23121 is a second straight line, and there is a fifth angle A5 between the second inner wall cut edge 23121 and the second horizontal plane b (it should be noted that the third angle A3 and the fifth angle A5 are both the angles between the second inner wall section and the second horizontal plane b, and the third angle A3 and the fifth angle A5 are used here to facilitate distinction in different embodiments), and the fifth angle A5 is greater than or equal to 90° and less than or equal to 160°. The specific value of the fifth angle A5 is not limited here, and is selected within the aforementioned range according to actual working conditions.

[0127] Furthermore, a third horizontal plane c passes through the third inner wall section and is perpendicular to the middle section A-A', and the third inner wall section and the third horizontal plane c have a sixth angle A6, and the sixth angle A6 is greater than 90° and less than or equal to 160°. The specific value of the sixth angle A6 is not limited here, and is selected within the aforementioned range according to actual working conditions.

[0128] Other technical features and technical effects are consistent with those of the fifth embodiment and will not be elaborated here.

[0129] Please refer to Fig.21 The self-piercing riveting lower die of the present invention also includes a tenth embodiment. The difference between the tenth embodiment and the ninth embodiment is that the structure of the third inner wall cut edge 23131 is changed, specifically:

[0130] The third inner wall cut edge 23131 is in a third curved shape and protrudes toward the direction close to the center axis L1 of the lower mold body 21 .

[0131] Other technical features and technical effects are consistent with those of the ninth embodiment and will not be elaborated here.

[0132] Please refer to Fig. 22 The self-piercing riveting lower die of the present invention also includes an eleventh embodiment. The difference between the eleventh embodiment and the tenth embodiment is that the structure of the third inner wall cut edge 23131 is changed, specifically:

[0133] The third inner wall cut edge 23131 is concave in a direction away from the central axis L1 of the lower mold body 21 and is curved.

[0134] Other technical features and technical effects are consistent with those of the tenth embodiment and will not be elaborated here.

[0135] Please refer to Fig.23 The self-piercing riveting lower die of the present invention also includes a twelfth embodiment. The difference between the twelfth embodiment and the tenth embodiment is that the structure of the third inner wall cut edge 23131 is changed, specifically:

[0136] The third inner wall cut edge 23131 may be bent into a concave-convex shape in a direction away from or close to the central axis L1 of the lower mold body 21 .

[0137] Other technical features and technical effects are consistent with those of the tenth embodiment and will not be elaborated here.

[0138] It should be noted that, in the present invention, the first straight line, the second straight line and the third straight line are all straight lines, and the "first", "second" and "third" therein are only for better distinguishing the first inner wall section 23111, the second inner wall section 23121 and the third inner wall section 23131.

[0139] Similarly, the first curve, the second curve and the third curve are all curves, and the “first”, “second” and “third” therein are only for better distinguishing the first inner wall cut edge 23111 , the second inner wall cut edge 23121 and the third inner wall cut edge 23131 .

[0140] Please refer to Figure 24-26 The upper mold body of the present invention has another embodiment, which is different from the first embodiment in that the structure of the upper mold body 31 is changed, specifically:

[0141] In this embodiment, a second boss 33 is provided on the lower end surface of the upper die body 31. When viewed in a direction perpendicular to the lower end surface of the upper die body 31, the second boss 33 is annular, and the feed channel 32 is located inside the second boss 33. The feed channel 32 includes an avoidance channel 321 and a feed channel 322, and the punch 5 can move back and forth in the avoidance channel 321 and the feed channel 322. The lower end of the avoidance channel 321 is located on the lower end surface of the second boss 33, the upper end of the avoidance channel 321 is connected to the lower end of the feed channel 322, and the upper end of the feed channel 322 is located on the upper end surface of the upper die body 31.

[0142] Specifically, as viewed from the projection of the upper mold body 31 on the mid-section AA′, the cross-sectional dimension of the avoidance channel 321 is greater than the cross-sectional dimension of the material delivery channel 32 .

[0143] The following formulas are also included:

[0144] Wherein R is the radius of the recessed portion 62, h is the height of the first boss 22, h1 is the thickness of the upper pushing portion 61, h2 is the thickness of the lower piercing portion 63, h3 is the thickness of the entire rivet 6, h4 is the height of the second boss 33, d4 is the outer diameter of the second boss 33, d5 is the inner diameter of the second boss 33, D1 is the first spacing L2, β is the seventh angle A7, and α is the first angle A1.

[0145] In this embodiment, the working principle is:

[0146] Taking a double-layer sheet material 4 to be riveted as an example, the first boss 22 and the second boss 33 cooperate to pre-press the sheet material 4 to be riveted, and the punch 5 fixes the rivet 6 from the feeding channel 32 and embeds the rivet 6 into the sheet material 4 to be riveted. The upper die body 31 is pressed down, the second boss 33 squeezes the upper sheet material 4 to be riveted, and the first boss 22 squeezes the lower sheet material 4 to be riveted, so that the sheet material 4 to be riveted undergoes plastic deformation after being squeezed by the first boss 22 and the second boss 33, the upper sheet material 4 to be riveted flows in the direction of avoiding the channel 321, and the lower sheet material 4 to be riveted flows in the direction of avoiding the channel 231, and finally fills the recessed portion 62 of the rivet 6, thereby improving the interlocking effect of the sheet material 4 to be riveted and the rivet 6.

[0147] Compared with the first embodiment, the first boss 22 can only make the lower layer of the sheet material 4 to be riveted have a tendency to flow toward the recessed portion 62 of the rivet 6. In this embodiment, the second boss 33 is provided on the lower end surface of the upper mold body 31, and an escape channel 321 is passed through the lower end surface of the second boss 33. Therefore, during riveting, the first boss 22 can be cooperated to make the upper layer of the sheet material 4 to be riveted and the lower layer of the sheet material 4 to be riveted have a tendency to flow toward the recessed portion 62 of the rivet 6 and fill the recessed portion 62 of the rivet 6. This structure can further enhance the interlocking effect of the sheet material 4 to be riveted and the rivet 6.

Claims

1. A self-piercing riveting lower die, characterized in that: include: A lower mold body (21), a first boss (22) is arranged on the upper end surface of the lower mold body (21), a blanking channel (23) runs through both ends of the lower mold body (21), and when viewed in a direction perpendicular to the upper end surface of the lower mold body (21), the projection of the blanking channel (23) is located inside the projection of the first boss (22); The material dropping channel (23) comprises an avoidance channel (231) and a material discharge channel (232); the upper port of the avoidance channel (231) is located on the upper end surface of the first boss (22); the lower end of the avoidance channel (231) is connected to the upper end of the material discharge channel (232); the cross-sectional dimension of the upper end of the avoidance channel (231) is greater than the cross-sectional dimension of the upper end of the material discharge channel (232).

2. The self-piercing riveting lower die according to claim 1, characterized in that: The avoidance channel (231) comprises a first sub-avoidance channel (2311), an upper port of the first sub-avoidance channel (2311) is located on the upper end surface of the first boss (22), a lower end of the first sub-avoidance channel (2311) is connected to the upper end of the discharge channel (232), and a cross-sectional dimension of the upper end of the first sub-avoidance channel (2311) is greater than a cross-sectional dimension of the upper end of the discharge channel (232).

3. The self-piercing riveting lower die according to claim 2, characterized in that: On the mid-section passing through the central axis of the lower mold body (21), the upper end of the first inner wall cut edge (23111) of the first sub-avoidance channel (2311) is connected to the upper end surface of the first boss (22), and the lower end of the first inner wall cut edge (23111) is connected to the inner wall of the discharge channel (232).

4. The self-piercing riveting lower die according to claim 3, characterized in that: On the mid-section, the first inner wall cut edge (23111) is a first straight line, or the first inner wall cut edge (23111) is a first curve.

5. The self-piercing riveting lower die according to claim 4, characterized in that: The first inner wall cut edge (23111) is a first straight line, and the first inner wall cut edge (23111) forms a first angle with a first horizontal plane perpendicular to the central axis of the lower mold body (21).

6. The self-piercing riveting lower die according to claim 5, characterized in that: The first angle ranges from 100° to 160°.

7. The self-piercing riveting lower die according to claim 4, characterized in that: The first inner wall cut edge (23111) is concave and curved in a direction away from the central axis of the lower mold body (21); or the first inner wall cut edge (23111) is convex and curved in a direction close to the central axis of the lower mold body (21); or the first inner wall cut edge (23111) is concave and convex.

8. The self-piercing riveting lower die according to claim 3, characterized in that: The avoidance channel (231) comprises a second sub-avoidance channel (2312), the upper end of the second sub-avoidance channel (2312) is connected to the lower end of the first sub-avoidance channel (2311), the lower end of the second sub-avoidance channel (2312) is connected to the upper end of the discharge channel (232), the cross-sectional dimension of the lower end of the first sub-avoidance channel (2312) is larger than the cross-sectional dimension of the upper end of the second sub-avoidance channel (2312), and the cross-sectional dimension of the upper end of the second sub-avoidance channel (2312) is larger than the cross-sectional dimension of the upper end of the discharge channel (232).

9. The self-piercing riveting lower die according to claim 8, characterized in that: On the mid-section passing through the central axis of the lower mold body (21), the upper end of the second inner wall section (23121) of the second sub-avoidance channel (2312) is connected to the lower end of the first inner wall section (23111) of the first sub-avoidance channel (2311), and the lower end of the second inner wall section (23121) is connected to the inner wall of the discharge channel (232).

10. The self-piercing riveting lower die according to claim 9, characterized in that: On the mid-section, the second inner wall cut edge (23121) is a second straight line, or the second inner wall cut edge (23121) is a second curve.

11. The self-piercing riveting lower die according to claim 10, characterized in that: The first inner wall cut edge (23111) is a first straight line, and the first inner wall cut edge (23111) forms a second angle with a first horizontal plane perpendicular to the central axis of the lower mold body (21), and the second angle is greater than or equal to 90° and less than or equal to 160°.

12. The self-piercing riveting lower die according to claim 11, characterized in that: The second inner wall cut edge (23121) is a second straight line, and the second inner wall cut edge (23121) forms a third angle with a second horizontal plane perpendicular to the central axis of the lower mold body (21).

13. The self-piercing riveting lower die according to claim 12, characterized in that: The third angle is greater than 90° and less than or equal to 160°.

14. The self-piercing riveting lower die according to claim 10, characterized in that: The second inner wall cut edge (23121) is concave in a direction away from the central axis of the lower mold body (21) and is curved; or the second inner wall cut edge (23121) is convex in a direction close to the central axis of the lower mold body (21) and is curved; or the second inner wall cut edge (23121) is concave-convex.

15. The self-piercing riveting lower die according to claim 9, characterized in that: The avoidance channel (231) includes a third sub-avoidance channel (2313), the upper end of the third sub-avoidance channel (2313) is connected to the lower end of the second sub-avoidance channel (2312), the lower end of the third sub-avoidance channel (2313) is connected to the upper end of the discharge channel (232), the cross-sectional dimension of the lower end of the second sub-avoidance channel (2312) is larger than the cross-sectional dimension of the upper end of the third sub-avoidance channel (2313), and the cross-sectional dimension of the upper end of the third sub-avoidance channel (2313) is larger than the cross-sectional dimension of the upper end of the discharge channel (232).

16. The self-piercing riveting lower die according to claim 15, characterized in that: On the mid-section passing through the central axis of the lower mold body (21), the upper end of the third inner wall section (23131) of the third sub-avoidance channel (2313) is connected to the lower end of the second inner wall section (23121) of the second sub-avoidance channel (2312), and the lower end of the third inner wall section (23131) is connected to the inner wall of the discharge channel (232).

17. The self-piercing riveting lower die according to claim 16, characterized in that: On the mid-section, the third inner wall cut edge (23131) is a third straight line, or the third inner wall cut edge (23131) is a third curve.

18. The self-piercing riveting lower die according to claim 17, characterized in that: The first inner wall cut edge (23111) is a first straight line, and the first inner wall cut edge (23111) forms a fourth angle with a first horizontal plane perpendicular to the central axis of the lower mold body (21), and the fourth angle is greater than 90° and less than or equal to 160°.

19. The self-piercing riveting lower die according to claim 18, characterized in that: The second inner wall cut edge (23121) is a second straight line, and the second inner wall cut edge (23121) forms a fifth angle with a second horizontal plane perpendicular to the central axis of the lower mold body (21), and the fifth angle is greater than or equal to 90° and less than or equal to 160°.

20. The self-piercing riveting lower die according to claim 19, characterized in that: The third inner wall section (23131) is a third straight line, and the third inner wall section (23131) forms a sixth angle with a third horizontal plane perpendicular to the central axis of the lower mold body (21), and the sixth angle is greater than 90° and less than or equal to 160°.

21. The self-piercing riveting lower die according to claim 17, characterized in that: The third inner wall cut edge (23131) is concave in a direction away from the central axis of the lower mold body (21) and is curved; or the third inner wall cut edge (23131) is convex in a direction close to the central axis of the lower mold body (21) and is curved; or the third inner wall cut edge (23131) is concave-convex.

22. The self-piercing riveting lower die according to claim 1, characterized in that: The outer wall of the first boss (22) and the top surface of the lower mold body (21) form a seventh angle.

23. The self-piercing riveting lower die according to claim 22, characterized in that: The seventh angle ranges from 100° to 160°.

24. The self-piercing riveting lower die according to claim 23, characterized in that: The upper end surface of the first boss (22) is annular, and there is a first spacing between the inner ring (221) and the outer ring (222) of the upper end surface of the first boss (22), and the first spacing is at least 4-6 times the height of the first boss (22).

25. A self-piercing riveting structure, characterized in that: comprising a self-piercing riveting lower die as described in any one of claims 1 to 24; It also includes an upper mold body (31), a material delivery channel (32) running through both ends of the upper mold body (31), and the material delivery channel (32) overlaps with the blanking channel (23) of the lower mold body (21) on the same vertical plane.

26. The self-piercing riveting structure according to claim 25, characterized in that: The lower end surface of the upper mold body (31) is a plane, and the lower end port of the material delivery channel (32) is located on the lower end surface of the upper mold body (31).

27. The self-piercing riveting structure according to claim 25, characterized in that: A second boss (33) is arranged on the lower end surface of the upper mold body (31); the feed channel (32) comprises an avoidance channel (321) and a feeding channel (322); the lower end of the avoidance channel (321) is located on the lower end surface of the second boss (33); the upper end of the avoidance channel (321) is connected to the lower end of the feeding channel (322).

28. A self-piercing riveting structure, characterized in that: comprising a self-piercing riveting lower die as described in any one of claims 1 to 24; It also includes an upper mold body (31), a material delivery channel (32) running through both ends of the upper mold body (31), and the material delivery channel (32) and the blanking channel (23) partially overlap on the same vertical plane; A second boss (33) is provided on the lower end surface of the upper mold body (31), and when viewed in a direction perpendicular to the lower end surface of the upper mold body (31), the material delivery channel (32) is located inside the second boss (33); The material conveying channel (32) comprises an avoidance channel (321) and a feeding channel (322); the lower end of the avoidance channel (321) is located on the lower end surface of the second boss (33); the upper end of the avoidance channel (321) is communicated with the lower end of the feeding channel (322); and a punch (5) is movably arranged in the material conveying channel (32); A rivet (6), wherein the rivet (6) is movably arranged in the feed channel (32); During riveting, the first boss (22) and the second boss (33) cooperate to press the sheet material (4) to be riveted, the punch (5) pushes the rivet (6) out of the feed channel (32) and embeds the rivet (6) into the sheet material (4) to be riveted, the upper die body (31) is pressed downward, the second boss (33) squeezes the upper end of the sheet material (4) to be riveted, the first boss (22) squeezes the lower end of the sheet material (4) to be riveted, the sheet material (4) to be riveted moves toward the avoidance channel and fills the recessed portion (62) on the side of the rivet (6).

29. The self-piercing riveting structure according to claim 28, characterized in that: The rivet (6) further comprises an upper pushing portion (61) and a lower piercing portion (63), and two ends of the recessed portion (62) are respectively connected to the upper pushing portion (61) and the upper piercing portion.

30. The self-piercing riveting structure according to claim 29, characterized in that: The following formulas are also included: Wherein, R is the radius of the recessed portion (62), h1 is the thickness of the upper pushing portion (61), h2 is the thickness of the lower piercing portion (63), h3 is the total thickness of the entire rivet (6), h4 is the height of the second boss (33), h is the height of the first boss (22), d4 is the outer diameter of the second boss (33), d5 is the inner diameter of the second boss (33), D1 is the first spacing between the inner ring (221) and the outer ring (222) of the upper end surface of the first boss (22), β is the seventh angle, and α is the first angle.

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