Heat-treatment-free self-penetrating rivet for ultrahigh-strength steel

Abstract

The utility model discloses a heat-treatment-free self-penetrating rivet for ultrahigh strength steel, which comprises a rivet head, a rivet rod and a skirt edge, the height of the skirt edge is 1.5-2mm, the internal structure of the skirt edge is composed of a first part, a second part, a third part and a fourth part, the first part is of a cylindrical structure, the thickness of the first part is 1.2-1.4 mm, the thickness of the second part is 1.2-1.4 mm, and the thickness of the third part is 1.2-1.4 mm. The second part is of a horn type circular truncated cone structure, the third part is of a cylinder structure, the fourth part is of a fillet structure, and the third part and the fourth part are matched to form a mushroom-shaped structure. According to the scheme, by increasing the internal space, the problem of the storage position of punched raw materials after the upper layer plate is pierced is solved; meanwhile, according to the scheme, the thickness of the rivet skirt is increased, and the strength of the rivet foot is improved; and secondly, the hardness of the whole part is reduced, the pressure needing to be applied to riveting deformation of the newly designed part is obviously reduced, and the riveting force of equipment is never reduced on the whole.

Description

Technical Field

[0001] The utility model relates to process manufacturing, in particular to a self-piercing rivet used for ultra-high-strength steel and free of heat treatment. Background Art

[0002] In terms of body design, the connection between ultra-high-strength steel above 1500MPa and heat-treatment-free cast aluminum is becoming more and more mainstream. Since it is a steel-aluminum connection, the traditional welding method can no longer meet the connection requirements. The conventional practice is to use SPR self-piercing rivets for riveting.

[0003] Traditional self-piercing rivets (SPR) cannot be used on this type of overlap, and rivet yielding is common. In response to the above technical problems, an existing solution provides a U-shaped rivet that can be used on steel-aluminum connections.

[0004] The existing U-shaped rivets are usually attached Figure 1 and attached Figure 2 There are two structures in Figure 1 In the rivet structure 1, the skirt is relatively thin. When the first layer of the board becomes stronger and stronger, this type of rivet is prone to yielding of the nail foot and riveting failure.

[0005] Figure 2 The inner hole space of the rivet structure 2 is too small, and the pierced upper plate material continues to accumulate, making the riveting force very large, exceeding the equipment's bearing limit.

[0006] Therefore, the existing U-shaped rivet structure has the technical problem of low reliability due to the above technical problems. Therefore, it can be seen that how to improve the reliability of the U-shaped rivet structure is a problem that needs to be solved in this field. Utility Model Content

[0007] In response to the technical problem of low reliability of existing U-shaped rivet structures, the utility model provides a self-piercing rivet for ultra-high strength steel and no heat treatment required, which can effectively overcome the technical problems of existing U-shaped rivets and greatly improve the reliability of the U-shaped rivet structure.

[0008] In order to achieve the above-mentioned purpose, the utility model provides a self-piercing rivet for ultra-high-strength steel and heat-treatment-free, including a rivet head, a rivet rod and a skirt, the height of the skirt is 1.5~2mm, and the internal structure of the skirt is composed of a first part, a second part, a third part and a fourth part. The first part is a cylindrical structure with a thickness of 1.2~1.4mm, the second part is a trumpet-type frustum structure, the third part is a cylindrical structure, and the fourth part is a chamfered structure. The third part and the fourth part cooperate to form a mushroom-shaped structure.

[0009] Furthermore, the overall height of the rivet is 4.5 mm to 5 mm.

[0010] Furthermore, the height between the nail head and the nail rod is 2.5 to 3.5 mm.

[0011] Furthermore, the arc edge expansion structure of the second portion has a radius of 1.64 to 1.66 mm.

[0012] Furthermore, the cross section of the trumpet-shaped frustum structure of the second portion is an arc-edge expansion structure, and its maximum expansion diameter is 4.0 mm to 4.2 mm.

[0013] Furthermore, the diameter of the third cylindrical part is 2.8-3.0 mm.

[0014] The utility model provides a self-piercing rivet for ultra-high-strength steel and heat treatment-free steel, which solves the problem of the storage position of the raw materials punched out after the upper plate is pierced by increasing the internal space.

[0015] At the same time, this solution increases the thickness of the rivet skirt and increases the strength of the rivet foot.

[0016] Secondly, the hardness of the overall parts is reduced, and the pressure required to apply to the riveting deformation of the newly designed parts is significantly reduced, and the riveting force of the equipment as a whole has never been reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a schematic diagram of the first structure of the existing rivet;

[0019] Figure 2 This is a schematic diagram of the second structure of the existing rivet.

[0020] Figure 3 Schematic diagram of the structure of the self-piercing rivet used for ultra-high-strength steel and heat treatment-free.

[0021] 100. Nail head 200. Nail shaft 300. Skirt 310. First part 320. Second part 330. Third part 340. Fourth part. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific illustrations.

[0023] The utility model provides a self-piercing rivet for ultra-high strength steel and heat treatment-free, see Figure 3The rivet is composed of three parts: a nail head 100, a nail rod 200 and a skirt 300, with an overall height of 4.5mm to 5mm. During the riveting process, the nail rod 200 penetrates the upper plate and forms a mushroom-shaped skirt in the lower plate. The skirt 300 fits tightly with the plate to form a firm riveting point.

[0024] Specifically, the rivet head 100 is the main force-bearing part of the connector, and its shape and size are determined according to the application and connection requirements. The rivet head shape includes flat head, round head, semi-circular head, etc. These shapes all help to improve the connection strength and stability.

[0025] The shank 200 of the rivet is the main part connecting the two objects, which runs through the two connectors and is fixed together. The length and diameter of the shank are also designed according to actual needs to ensure the firmness and stability of the connection.

[0026] The skirt 300 of the rivet plays a role of positioning and supporting in the connection process. During installation, the skirt needs to withstand a certain impact force to ensure that the rivet can fully penetrate the connector and form a strong connection.

[0027] The overall height L3 of the skirt 300 in this solution is L1-L2. In this solution, preferably L1=4.5-5mm, L2=2.5-3.5mm. Therefore, the overall height L3 of the skirt 300 is 1.5-2mm, preferably 2mm. Figure 2 The internal structure of the existing rivet skirt 300 increases the internal space, which can effectively overcome the technical problem that the existing rivets have too small inner hole space, and the pierced upper plate broken materials continue to accumulate, resulting in a very large riveting force that exceeds the equipment's bearing limit.

[0028] The inner structure of the skirt 300 is composed of a first portion 310 , a second portion 320 , a third portion 330 and a fourth portion 340 .

[0029] The first part 310 is a cylinder with a circular ring cross-section. The thickness of the cylinder is 1.2 to 1.4 mm, preferably 1.3 mm. Compared with the existing rivet structure, the wall thickness is increased, which can improve the strength of the skirt 300.

[0030] The second portion 320 is a trumpet-shaped frustum structure, and its cross section is an expansion structure with an arc edge. Its radius is 1.64 to 1.66 mm, preferably 1.65 mm, and its maximum expansion diameter is 4.0 mm to 4.2 mm.

[0031] The third part 330 cooperates with the fourth part to form a mushroom-shaped structure, wherein the third part 330 is a cylinder with a circular ring cross-section and a diameter of 2.8 to 3.0 mm, preferably 2.9 mm, and the fourth part 340 is a rounded structure.

[0032] The self-piercing rivet for ultra-high-strength steel and heat-treatment-free formed by the above-mentioned solution is used as an example to illustrate its working process in a specific application. It should be noted here that this working process is only an example and does not limit this solution.

[0033] The riveting process of the rivet formed by the above scheme can be divided into four stages: clamping, piercing, expansion and punching.

[0034] During the clamping stage, the blank holder presses the sheet to be riveted downward, and the rivet is also driven by the punch to pre-press the sheet vertically downward.

[0035] During the piercing stage, the punch moves downward, pushing the rivet to pierce the upper sheet material. At the same time, the rivet also drives the lower sheet material to undergo plastic deformation into the die.

[0036] During the expansion phase, the rivet skirt gradually opens, and the underlying sheet material undergoes plastic deformation, gradually filling the die. Under the combined action of the punch and die boss, the rivet leg expands outward and embeds into the underlying sheet, forming a mechanical interlocking structure between the rivet and the sheet material.

[0037] In the punching and riveting completion stage, when the punch presses the rivet down until the rivet head is in close contact and flush with the upper surface of the upper sheet, the riveting is completed. At this time, the blank holder releases the blank holding force, the punch returns to the initial position, and the punching and riveting is completed.

[0038] In summary, the self-piercing rivets for ultra-high-strength steel and heat-treatment-free steel solve the problem of the storage location of the raw materials punched out after the upper plate is pierced by increasing the internal space.

[0039] At the same time, this solution increases the thickness of the rivet skirt and increases the strength of the rivet foot.

[0040] Secondly, the hardness of the overall parts is reduced, and the pressure required to apply to the riveting deformation of the newly designed parts is significantly reduced, and the riveting force of the equipment as a whole has never been reduced.

[0041] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention. The scope of protection claimed in this invention is defined by the appended claims and their equivalents.

Claims

1. A self-piercing rivet for ultra-high strength steel and heat treatment-free steel, comprising a rivet head, a rivet stem and a skirt, characterized in that: The height of the skirt is 1.5 to 2 mm, and the internal structure of the skirt is composed of a first part, a second part, a third part and a fourth part. The first part is a cylindrical structure with a thickness of 1.2 to 1.4 mm, the second part is a trumpet-shaped frustum structure, the third part is a cylindrical structure, and the fourth part is a chamfered structure. The third part and the fourth part cooperate to form a mushroom-shaped structure.

2. The self-piercing rivet for ultra-high strength steel and heat treatment-free according to claim 1, characterized in that: The overall height of the rivet is 4.5 mm to 5 mm.

3. The self-piercing rivet for ultra-high strength steel and heat treatment-free according to claim 1, characterized in that: The height between the nail head and the nail rod is 2.5-3.5 mm.

4. The self-piercing rivet for ultra-high strength steel and heat treatment-free according to claim 1, characterized in that: The arc-edge expansion structure of the second portion has a radius of 1.64 to 1.66 mm.

5. The self-piercing rivet for ultra-high strength steel and heat treatment-free according to claim 1, characterized in that: The cross section of the trumpet-shaped frustum structure of the second part is an arc-edge expansion structure, and the maximum expansion diameter thereof is 4.0 mm to 4.2 mm.

6. The self-piercing rivet for ultra-high strength steel and heat treatment-free according to claim 1, characterized in that: The diameter of the third cylindrical part is 2.8-3.0 mm.

Images