Self-piercing rivets and methods for manufacturing fastening structures

Abstract

To provide a self-pierce rivet capable of suppressing cracks of a lower side fastened member with a simple configuration while maintaining manufacturing efficiency, and a method for manufacturing a fastening structure.SOLUTION: A self-pierce rivet 10 has a head part 10A, an outside cylindrical part 10B extending from the head part 10A and formed into a cylindrical shape, and an inside cylindrical part 10C extending from the head part 10A, spaced apart inside the outside cylindrical part 10B and formed into a cylindrical shape. In a method for manufacturing a fastening structure, the self-pierce rivet 10 is driven into an overlapping part 16 of a first fastened member 12 and a second fastened member 14 to fasten the first fastened member 12 and the second fastened member 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a self-piercing rivet and a method for manufacturing a fastening structure.

Background Art

[0002] Various techniques related to self-piercing rivets have been disclosed (see, for example, Patent Document 1 below). In order to ensure the fastening strength by fastening a plurality of fastened members with such a self-piercing rivet, it is necessary to make the cylindrical portion (also referred to as the body portion or the leg portion) of the self-piercing rivet thick to some extent. On the other hand, a configuration in which the thickness of the cylindrical portion of the self-piercing rivet is thick is disadvantageous in suppressing cracking of the lower fastened member (the lowermost fastened member) caused by driving the self-piercing rivet.

[0003] Here, as a self-piercing rivet with a reduced thickness of the cylindrical portion, there is a technique disclosed in Patent Document 1 below. In this prior art, the self-piercing rivet has a double-tube structure composed of an outer tube and an inner tube. For the overlapping portion of a plurality of connected members, the driving of the body portion of the outer tube is performed first, and the driving of the body portion of the inner tube is performed with a time difference. In the completed driving state, the body portion of the outer tube and the body portion of the inner tube are in contact with each other and integrated, and the tip side thereof is configured to bite into the inside of the lower connected member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the aforementioned prior art, the timing of pressing in the outer tube body and the timing of pressing in the inner tube body are staggered, so there is room for improvement in terms of manufacturing efficiency, as well as in terms of simplifying the structure.

[0006] The present invention aims to provide a self-piercing rivet and a method for manufacturing a fastening structure that can suppress cracking of the lower fastened member with a simple configuration while maintaining manufacturing efficiency, taking the above facts into consideration. [Means for solving the problem]

[0007] The self-piercing rivet of the present invention as described in claim 1 is a self-piercing rivet that fastens a plurality of fastened members by being driven into the overlapping portion of a plurality of fastened members, comprising a head and extending from the head and formed in a cylindrical shape, At its tip, an inclined inner surface is formed in which the inner diameter gradually increases toward the tip, When driven into the overlapping portion, the tip side deforms radially outward. It is configured in such a way An outer cylindrical portion, and a portion extending from the head and spaced apart inside the outer cylindrical portion, which is formed in a cylindrical shape, At its tip, an inclined outer surface is formed in which the outer diameter gradually decreases toward the tip, When driven into the overlapping portion, the tip side diameter It deforms inward in that direction. It is configured in such a way It has an inner cylindrical part.

[0008] According to the above configuration, the outer cylindrical portion and the inner cylindrical portion extend from the head, and the inner cylindrical portion is provided spaced apart inside the outer cylindrical portion. Here, the tip of the outer cylindrical portion is formed with an inclined inner surface whose inner diameter gradually increases toward the tip, so that when the outer cylindrical portion is driven into the overlapping section of multiple fastened members, the tip of the outer cylindrical portion deforms radially outward. The tip of the inner cylindrical portion is formed with an inclined outer surface whose outer diameter gradually decreases toward the tip, so that when the inner cylindrical portion is driven into the overlapping section of multiple fastened members, the tip of the inner cylindrical portion deforms radially inward. As a result, When a self-piercing rivet is driven into the overlapping section of multiple fastened members, the outer cylindrical section and the inner cylindrical section, which are spaced apart from each other, are driven into the overlapping section together. The outer cylindrical portion deforms radially outward at its tip due to the force acting on its inclined inner surface, and bites into the interior of the overlapping portion. The inner cylindrical portion deforms radially inward at its tip due to the force acting on its inclined outer surface, and bites into the interior of the overlapping portion. While maintaining manufacturing efficiency, for example, the thickness of the outer cylindrical part and the inner cylindrical part can be made thinner in proportion to a single cylindrical part. The overlapping parts can be securely fastened using self-piercing rivets. Furthermore, by reducing the thickness of both the outer and inner cylindrical parts, the lower fastened member becomes less likely to crack when the self-piercing rivet is driven in.

[0011] Claim 2The method for manufacturing the fastening structure of the present invention described in Claim 1 The self-piercing rivets described are driven into the overlapping portions of the multiple fastened members to be fastened together.

[0012] According to the above configuration, when the self-piercing rivet is driven into the overlapping portion of multiple fastened members, the outer cylindrical portion and the inner cylindrical portion, which are spaced apart from each other, are driven into the overlapping portion together, the tip of the outer cylindrical portion deforms radially outward, and the tip of the inner cylindrical portion diameter It deforms inward in the direction. Therefore, while maintaining manufacturing efficiency, for example, the thickness of the outer cylindrical part and the inner cylindrical part can be made thinner compared to a single cylindrical part in proportion to the outer cylindrical part. The overlapping parts can be securely fastened using self-piercing rivets. Furthermore, by reducing the thickness of both the outer and inner cylindrical parts, the lower fastened member becomes less likely to crack when the self-piercing rivet is driven in. [Effects of the Invention]

[0013] As described above, the present invention has the excellent effect of suppressing cracking of the lower fastened member with a simple configuration while maintaining manufacturing efficiency. [Brief explanation of the drawing]

[0014] [Figure 1] This is a cross-sectional view showing the self-piercing rivet, the first fastened member, and the second fastened member according to the first embodiment, in the state before the self-piercing rivet is driven in. [Figure 2] This is a cross-sectional view showing a fastening structure manufactured by the manufacturing method of a fastening structure according to the first embodiment. [Figure 3] This is a cross-sectional view showing an example of a fastening device used in the manufacturing method of a fastening structure according to the first embodiment, together with a first fastened member, a second fastened member, and a self-piercing rivet. [Figure 4] Figure 3 is a cross-sectional view showing the state in which a self-piercing rivet is being driven into the overlapping portion between the first and second fastened members, starting from the state shown in Figure 3. [Figure 5]It is a cross-sectional view showing a self-piercing rivet, a first fastening member, and a second fastening member according to a second embodiment in a state before driving the self-piercing rivet. [Figure 6] It is a cross-sectional view showing a fastening structure manufactured by a manufacturing method of a fastening structure according to a second embodiment.

Embodiments for Carrying Out the Invention

[0015] [First Embodiment] The A self-piercing rivet and a method for manufacturing a fastening structure according to Embodiment 1 will be described with reference to FIGS. 1 to 4. Note that the first embodiment is a reference example and not an embodiment of the present invention.

[0016] FIG. 1 shows a cross-sectional view of a self-piercing rivet 10, and an example of a first fastening member 12 and a second fastening member 14 as fastening members in a state before driving the self-piercing rivet 10.

[0017] The self-piercing rivet 10 is made of special steel such as chrome molybdenum steel. The self-piercing rivet 10 is a fastener that fastens the plurality of fastening members (in FIG. 1, the first fastening member 12 and the second fastening member 14) by being driven into an overlapping portion of the plurality of fastening members (in FIG. 1, the overlapping portion 16 of the first fastening member 12 and the second fastening member 14).

[0018] The self-piercing rivet 10 has a head 10A, an outer cylindrical portion 10B integrally extending from the head 10A and formed in a cylindrical shape, and an inner cylindrical portion 10C integrally extending from the head 10A and provided inside the outer cylindrical portion 10B at a distance and formed in a cylindrical shape. The inner cylindrical portion 10C is set to be thinner than the outer cylindrical portion 10B.

[0019] The tip of the outer cylindrical portion 10B has an inclined inner surface 10X formed thereon, with the inner diameter gradually increasing toward the tip. This causes the tip of the outer cylindrical portion 10B to deform radially outward when it is driven into the overlapping portion 16 between the first fastened member 12 and the second fastened member 14. Similarly, the tip of the inner cylindrical portion 10C has an inclined inner surface 10Y formed thereon, with the inner diameter gradually increasing. This causes the tip of the inner cylindrical portion 10C to deform radially outward when it is driven into the overlapping portion 16 between the first fastened member 12 and the second fastened member 14.

[0020] The tip positions of the outer cylindrical portion 10B and the inner cylindrical portion 10C are aligned in the axial direction of the self-piercing rivet 10. In Figure 1, arrow A indicates the direction in which the self-piercing rivet 10 is driven into the overlapping portion 16 of the first fastened member 12 and the second fastened member 14.

[0021] The first fastened member 12 and the second fastened member 14 are, for example, both made of metal. More specifically, the first fastened member 12 is made of aluminum alloy, and the second fastened member 14 is made of steel. Also, the first fastened member 12 is, for example, a die-cast product formed by die-casting. The first fastened member 12 and the second fastened member 14 are, for example, components for a vehicle.

[0022] The manufacturing method of the fastening structure in this embodiment is to manufacture the fastening structure 20 by driving a self-piercing rivet 10 into the overlapping portion 16 of the first fastened member 12 and the second fastened member 14, thereby fastening the first fastened member 12 and the second fastened member 14 as shown in Figure 2.

[0023] Next, an example of a device used in the manufacturing method of the fastening structure 20 will be described with reference to Figure 3. Figure 3 shows an example of a fastening device 30 used in the manufacturing method of the fastening structure according to this embodiment.

[0024] As shown in Figure 3, the fastening device 30 includes a die 32 as a support member that supports the first fastened member 12 from the side opposite to the side in which the self-piercing rivet 10 is driven in. The die 32 is made of, for example, steel and has a general support surface 32A that supports the first fastened member 12 from below. The die 32 also has a recess 32B that contacts the deformed portion of the first fastened member 12 when it is deformed by the driving in of the self-piercing rivet 10. The recess 32B is recessed relative to the general support surface 32A and is circular in shape when viewed from above.

[0025] The fastening device 30 also includes a cylinder 36 and a punch 38. The cylinder 36 is cylindrical in shape and into which the self-piercing rivet 10 can be inserted. The cylinder 36 is positioned so that its axis corresponds to the center of the recess 32B of the die 32, and presses the first fastened member 12 and the second fastened member 14, which are supported by the die 32, against the general support surface 32A of the die 32. The punch 38 is a cylindrical member and is movable within the cylinder 36 in the axial direction by a drive device (not shown), and is configured to press the self-piercing rivet 10 inserted into the cylinder 36 from above. In the figure, the direction in which the punch 38 presses the self-piercing rivet 10 is indicated by arrow P.

[0026] Next, the manufacturing method of the fastening structure will be explained with reference to Figures 3 and 4.

[0027] First, as shown in Figure 3, the first fastened member 12 is supported on the general support surface 32A of the die 32, and the second fastened member 14 is placed on top of the first fastened member 12. In this embodiment, as an example, the end of the first fastened member 12 (the end perpendicular to the plane of the paper in Figure 3) is supported by the die 32. Next, the first fastened member 12 and the second fastened member 14 are sandwiched between the lower end surface of the cylinder 36 and the general support surface 32A of the die 32.

[0028] Next, the self-piercing rivet 10 inside the cylinder 36 is pushed from above by the punch 38. As a result, as shown in Figure 4, the self-piercing rivet 10 descends, and the outer cylindrical portion 10B and inner cylindrical portion 10C of the self-piercing rivet 10 penetrate the second fastened member 14, causing the first fastened member 12, which is pressed by the self-piercing rivet 10 and the second fastened member 14, to deform toward the recess 32B side of the die 32. A part of the first fastened member 12 deforms along the recess 32B, and the ends of the outer cylindrical portion 10B and inner cylindrical portion 10C of the self-piercing rivet 10 deform radially outward as they bite into the first fastened member 12. After that, the cylinder 36 and punch 38 are raised, and the fastening structure 20 shown in Figure 2 is removed from the fastening device 30.

[0029] Next, the operation and effects of the embodiment described above will be explained.

[0030] In this embodiment, as shown in Figure 4, when the self-piercing rivet 10 is driven into the overlapping portion 16 between the first fastened member 12 and the second fastened member 14, the outer cylindrical portion 10B and the inner cylindrical portion 10C, which are spaced apart from each other, are driven into the overlapping portion 16 together, and the tip ends of the outer cylindrical portion 10B and the inner cylindrical portion 10C each deform radially outward. Therefore, while maintaining manufacturing efficiency, it is possible to maintain fastening strength (joint strength) while making the thickness of the outer cylindrical portion 10B and the inner cylindrical portion 10C thinner compared to, for example, a single cylindrical portion. In addition, because the thickness of the outer cylindrical portion 10B and the inner cylindrical portion 10C is thinned, the first fastened member 12, which is the lower fastened member, is less likely to crack when the self-piercing rivet 10 is driven in.

[0031] As described above, according to this embodiment, it is possible to suppress cracking of the first fastened member 12 (lower fastened member) with a simple configuration while maintaining manufacturing efficiency.

[0032] [Second Embodiment] next , the The method for manufacturing the self-piercing rivet and fastening structure according to the second embodiment will be explained with reference to Figures 5 and 6. The second embodiment is an embodiment of the present invention. The first fastened member 12 and the second fastened member 14, which are fastened members, have substantially the same configuration as those in the first embodiment, and for convenience, they are given the same reference numerals and their description is omitted.

[0033] The self-piercing rivet 40 shown in Figure 5 is a fastener that fastens multiple fastened members (the first fastened member 12 and the second fastened member 14 in Figure 5) by being driven into the overlapping portion of the multiple fastened members (the overlapping portion 16 of the first fastened member 12 and the second fastened member 14 in Figure 5). The self-piercing rivet 40 has a head 40A, an outer cylindrical portion 40B that extends integrally from the head 40A and is formed in a cylindrical shape, and an inner cylindrical portion 40C that extends integrally from the head 40A and is provided spaced apart inside the outer cylindrical portion 40B. The inner cylindrical portion 40C is formed in a cylindrical shape and is set to be thinner than the outer cylindrical portion 40B.

[0034] The tip of the outer cylindrical portion 40B has an inclined inner surface 40X formed thereon, in which the inner diameter gradually increases toward the tip. As a result, when the outer cylindrical portion 40B is driven into the overlapping portion 16 between the first fastened member 12 and the second fastened member 14, the tip of the outer cylindrical portion 40B is deformed radially outward. In addition, the tip of the inner cylindrical portion 40C has an inclined outer surface 40Y formed thereon, in which the outer diameter gradually decreases toward the tip. As a result, when the inner cylindrical portion 40C is driven into the overlapping portion 16 between the first fastened member 12 and the second fastened member 14, the tip of the inner cylindrical portion 40C is deformed radially inward.

[0035] The tip positions of the outer cylindrical portion 40B and the inner cylindrical portion 40C are aligned in the axial direction of the self-piercing rivet 40. In Figure 5, arrow B indicates the direction in which the self-piercing rivet 40 is driven into the overlapping portion 16 of the first fastened member 12 and the second fastened member 14.

[0036] In the manufacturing method of the fastening structure of the second embodiment, the self-piercing rivet 40 is driven into the overlapping portion 16 of the first fastened member 12 and the second fastened member 14 to fasten the first fastened member 12 and the second fastened member 14 as shown in Figure 6, thereby manufacturing the fastening structure 50. In the step of driving the self-piercing rivet 40 into the overlapping portion 16, the same type of fastening device 30 (see Figures 3 and 4) described in the first embodiment is used.

[0037] In the second embodiment described above, similar to the first embodiment, it is possible to maintain manufacturing efficiency while reducing the thickness of the outer cylindrical portion 40B and the inner cylindrical portion 40C compared to a single cylindrical portion, while maintaining fastening strength (joint strength). Furthermore, by reducing the thickness of the outer cylindrical portion 40B and the inner cylindrical portion 40C, the first fastened member 12, which is the lower fastened member, becomes less likely to crack when the self-piercing rivet 40 is driven in.

[0038] Thus, the second embodiment also makes it possible to suppress cracking of the first fastened member 12 (lower fastened member) with a simple configuration while maintaining manufacturing efficiency.

[0039] Furthermore, in the second embodiment, as shown in Figure 5, the tip of the outer cylindrical portion 40B has an inclined inner surface 40X whose inner diameter gradually increases toward the tip, and the tip of the inner cylindrical portion 40C has an inclined outer surface 40Y whose outer diameter gradually decreases toward the tip. Therefore, as shown in Figure 6, when the self-piercing rivet 40 is driven into the overlapping portion 16, the outer cylindrical portion 40B deforms radially outward toward the tip due to the force received by the inclined inner surface 40X (see Figure 5) during the driving process and bites into the interior of the overlapping portion 16, and the inner cylindrical portion 40C deforms radially inward toward the tip due to the force received by the inclined outer surface 40Y (see Figure 5) during the driving process and bites into the interior of the overlapping portion 16. Therefore, the overlapping portion 16 can be firmly fastened with the self-piercing rivet 40.

[0040] [Supplementary explanation of the embodiment] In the first and second embodiments shown in Figures 1 to 6, the tip positions of the outer cylindrical parts 10B and 40B and the tip positions of the inner cylindrical parts 10C and 40C are aligned in the axial direction of the self-piercing rivets 10 and 40. However, as a modification of the first and second embodiments, a configuration can be adopted in which the tip positions of the outer cylindrical parts (10B and 40B) and the tip positions of the inner cylindrical parts (10C and 40C) are offset in the axial direction of the self-piercing rivets (10 and 40).

[0041] Furthermore, in the first and second embodiments described above, the inner cylindrical parts 10C and 40C are set to be thinner than the outer cylindrical parts 10B and 40B. However, as a variation of the first and second embodiments described above, it is also possible to adopt a configuration in which the inner cylindrical parts (10C and 40C) and the outer cylindrical parts (10B and 40B) are set to be of equal thickness, or a configuration in which the inner cylindrical parts (10C and 40C) are set to be thicker than the outer cylindrical parts (10B and 40B).

[0042] Furthermore, in the first and second embodiments described above, the second fastened member 14 is made of steel as an example, but as a modification of the first and second embodiments described above, the second fastened member (14) may be made of an aluminum alloy. To add to this, in the first and second embodiments described above, self-piercing rivets 10 and 40 are applied to fastening (joining) dissimilar materials, but self-piercing rivets (10 and 40) may be applied to fastening (joining) similar materials.

[0043] Furthermore, in the first and second embodiments described above, the self-piercing rivets 10 and 40 are driven into the overlapping portion 16 of the first fastened member 12 and the second fastened member 14. However, as a modification of the first and second embodiments described above, the self-piercing rivets (10 and 40) may be driven into the overlapping portions of three or more fastened members.

[0044] Furthermore, the first and second embodiments described above, as well as the various modifications described above, can be combined and implemented as appropriate.

[0045] Although an example of the present invention has been described above, the present invention is not limited to the above, and it is of course possible to implement it in various ways without departing from its spirit. [Explanation of symbols]

[0046] 10 Self-piercing rivets 10A head 10B Outer cylindrical part 10C Inner cylindrical part 12 First fastened member 14 Second fastened member 16 Overlapping section 20 Fastening structure 40 Self-piercing rivets 40A head 40B Outer cylindrical part 40C Inner cylindrical part 40X Inclined inner surface 40Y sloped outer surface 50 Fastening structure

Claims

1. A self-piercing rivet that fastens multiple fastened members by being driven into the overlapping portions of multiple fastened members, The head and An outer cylindrical portion extending from the head, formed in a cylindrical shape, and having an inclined inner surface at its tip with an inner diameter that gradually increases toward the tip, is configured such that when driven into the overlapping portion, the tip side deforms radially outward; An inner cylindrical portion extends from the head and is provided spaced apart inside the outer cylindrical portion, formed in a cylindrical shape, and has an inclined outer surface at its tip, with the outer diameter gradually decreasing toward the tip, so that when it is driven into the overlapping portion, the tip side deforms radially inward; Self-piercing rivets.

2. A method for manufacturing a fastening structure, comprising driving a self-piercing rivet according to claim 1 into the overlapping portions of a plurality of fastened members to fasten the plurality of fastened members.

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