Net-Shaped Substrate Materials for Substrate Bonding

Abstract

An assembly includes an upper base plate, a lower base plate, and a self-piercing rivet. The lower base plate defines a preformed interior cavity and a preformed exterior contour adjacent to the interior cavity, thereby defining a variable thickness wall. The self-piercing rivet extends through the upper base plate and into the preformed interior cavity of the lower base plate.

Description

Technical Field

[0001] The present disclosure relates to the joining of various materials in an assembly, including advanced, high strength and light weight dissimilar materials. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] As the automotive industry continues to focus on reducing vehicle weight to meet customer expectations for fuel economy and CAFE (Corporate Average Fuel Economy) requirements, interest in alternative materials including the application of carbon fiber composites has increased. In body-in-white structures, joining methods have traditionally relied on resistance spot welding (e.g., in steel structures).

[0004] In the case of aluminum-intensive vehicles and other mixed metal joining applications, self-piercing rivet technology dominates. One advantage of self-piercing rivet technology is that it is a high-yield assembly process. Self-piercing rivet technology is compatible with adhesives, and the two methods can be used together. However, the challenge faced by self-piercing rivet technology is that the ductility of the substrate material must be sufficient to form a "button" (i.e., a protrusion), which is the result of forming a joint and the necessary deformation to provide a mechanical interlock. When the ductility possessed by the composite part is not sufficient to form a button on the front side, the fibers may be exposed through the breaks in this surface. Surface fractures and fiber displacement are undesirable because they can reduce the durability of the joint and lead to premature failure. Due to self-piercing rivets, the fibers in the area where the rivet is inserted can cause surface fractures or fiber displacement.

[0005] Composite materials, such as carbon fiber, glass fiber, or natural fiber composites, can be limited in applications due to challenges associated with joining parts together. Oftentimes, these composites have limited ductility and are not well adapted to the large displacements and deformations required to join parts together using self-piercing rivets. Other non-composite materials that are stronger and lighter are also often brittle and challenging to join using surface plasmon resonance (SPR) techniques.

[0006] The present disclosure solves assembly problems such as the joining of advanced, high-strength and light-weight materials. Summary of the invention

[0007] In one form, an assembly is provided that includes an upper base plate, a lower base plate, and a self-piercing rivet. The lower base plate defines a pre-formed interior cavity and a pre-formed exterior contour adjacent to the interior cavity, thereby defining a variable thickness wall. The self-piercing rivet extends through the upper base plate and into the pre-formed interior cavity of the lower base plate. The pre-formed interior cavity of the lower base plate may or may not be plastically deformed after the self-piercing rivet is installed.

[0008] In one form, the lower substrate is an aluminum casting or an aluminum extrusion. In another form, the lower substrate is a composite material. In one form, the preformed internal cavity defines a circular groove having a raised central area, and in another form, the preformed external profile defines a closed cylinder. The preformed external profile may further define a rounded area extending between the lower surface of the lower substrate and the cylinder. In general, the preformed internal cavity is configured to guide the flaring of the self-piercing rivet.

[0009] In another form, a dimpled substrate for use in an assembly having joined substrates is provided. The dimpled substrate defines at least one preformed interior cavity and at least one preformed exterior contour adjacent the interior cavity, thereby defining a variable thickness wall. The preformed interior cavity is configured to receive a fastening system that plastically deforms at least one of the substrates during joining.

[0010] In yet another form, an assembly is provided that includes an upper base plate, a lower base plate, and a plurality of self-piercing rivets. The lower base plate defines a plurality of pre-formed interior cavities and a corresponding plurality of pre-formed exterior contours adjacent the interior cavities, thereby defining a variable thickness wall therebetween. The plurality of self-piercing rivets extend through the upper base plate and into the pre-formed interior cavities of the lower base plate. The pre-formed interior cavities are configured to guide the outward expansion of the self-piercing rivets.

[0011] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0013] Figure 1 is a cross-sectional view of a joint assembly constructed in accordance with the teachings of the present disclosure;

[0014] Figure 2 According to the teachings of this disclosure Figure 1a top perspective view of a lower substrate of a bonded assembly, the lower substrate having a preformed internal cavity;

[0015] Figure 3 yes Figure 2 A bottom perspective view of a lower substrate;

[0016] Figure 4 yes Figure 2 A cross-sectional view of a lower substrate;

[0017] Figure 5 is a cross-sectional view of a variation of a lower base plate of a joint assembly constructed in accordance with the teachings of the present disclosure; and

[0018] Figure 6 is a cross-sectional view of upper and lower base plates and a self-piercing rivet tool including a rivet punch and a back-up die, with the self-piercing rivet in position to be driven into the upper and lower base plates.

[0019] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0020] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0021] See also Figure 1 , the joined composite material or assembly 10 includes a lower substrate 12, an upper substrate 14, and at least one self-piercing rivet 20 that secures the lower substrate 12 to the upper substrate 14. Although only one self-piercing rivet 20 is shown, the joined composite material or assembly 10 may include multiple self-piercing rivets 20 spaced across the surface of the joined composite material or assembly 10. The lower substrate 12 may be a pitted substrate and include at least one preformed outer profile in the form of a button-like protrusion or "button" 18. The button 18 extends downward from the lower surface 22 of the lower substrate 12 and is disposed in a predetermined position where the corresponding self-piercing rivet 20 is planned to be inserted into the lower substrate 12. The upper substrate 14 may be made of steel, aluminum, fiber reinforced composite material, or other materials. The lower substrate 12 may be a cast component, a molded component, a 3D printed component, or the like. In various forms of the present disclosure, the substrate 12 is an aluminum casting, an aluminum extrusion, or a composite material.

[0022] See also Figure 2 and Figure 3 , the button 18 of the lower substrate 12 is configured as a closed cylinder having a peripheral wall 24 and a bottom wall 26. The peripheral wall 24 and the bottom wall 26 together define a preformed outer profile having a preformed interior cavity 28. The preformed interior cavity 28 is configured to receive a fastening system, such as a self-piercing rivet 20, which plastically deforms at least one of the lower substrate 12 and the upper substrate 14 during joining.

[0023] See also Figure 4 , the bottom wall 26 has a variable thickness and has a maximum thickness adjacent the center region, thereby defining a raised center region 30. A circular or annular groove 32 is defined between the raised center region 30 and the sidewalls 24 of the button 18 and surrounds the raised center region 30. In one form of the present disclosure, the button 18 has a substantially flat bottom surface 34. The raised center region 30 has a top surface 36 that is lower than the lower surface 22 of the lower substrate 12.

[0024] See also Figure 5 The lower substrate 50 according to the modification of the present disclosure is similar in structure to Figures 1 to 4 1. The lower substrate 12 of the present invention is provided with a button 52 that defines a preformed interior cavity 54 and includes a bottom wall 62. The bottom wall 62 has a variable thickness and has a maximum thickness adjacent to a central region, thereby defining a raised central region 64. An annular or circular groove 66 is defined within the preformed interior cavity 54 and around the raised central region 64. The raised central region 64 defines a top surface 68 that is raised to a height above a lower surface 72 of the lower substrate 50. The bottom surface 70 of the bottom wall 62 of the button 52 is substantially flat. The button 52 also includes a rounded area 74 that joins the bottom surface 70 of the bottom wall 62 to the lower surface 72 of the lower substrate 50 where the button is not formed.

[0025] See also Figure 6 To join the lower substrate 12 to the upper substrate 14, the upper substrate 14 is placed on top of the lower substrate 12 in a self-piercing rivet tool 80. The self-piercing rivet tool 80 includes a rivet punch 82 and a backing die 84. The preformed internal cavity 28 of the button 18 of the lower substrate 12 is closed by the upper substrate 14.

[0026] The self-piercing rivet 20 is placed within the self-piercing rivet tool 80 and placed immediately above the pre-formed interior cavity 28 of the lower substrate 12. The self-piercing rivet 20 has an insertion end 88 to pierce the upper substrate 14 and insert into the pre-formed interior cavity 28 of the lower substrate 12 to engage the bottom wall 26 of the button 18. It should be understood that the reference to the top side is not limiting and the lower substrate 12 and upper substrate 14 may be arranged in any orientation.

[0027] review Figure 1, when the self-piercing rivet 20 is fully inserted into the joined composite material or assembly 10, the insertion end 88 of the self-piercing rivet 20 diverges as the self-piercing rivet 20 is driven through the upper base plate 14. The preformed internal cavity 28 is configured to guide the outward expansion of the self-piercing rivet 20. The portion of the upper base plate 14 adjacent to the self-piercing rivet 20 undergoes plastic deformation. Material from the upper base plate 14 can be deformed and directed into the preformed internal cavity 28 to fill the preformed internal cavity 28. The radially displaced material 92 fills between the side of the self-piercing rivet 20 and the button 18. The axially displaced material 94 fills between the insertion end 88 of the self-piercing rivet 20 and the bottom wall 26 of the button 18 of the lower base plate 12.

[0028] The self-piercing rivet 20 penetrates the lower substrate 12 to form a mechanical interlock, thereby joining the lower substrate 12 and the upper substrate 14 together. The pre-formed internal cavity 28 of the lower substrate 12 may or may not be plastically deformed after the self-piercing rivet 20 is installed. The pre-formed button 18 and the pre-formed internal cavity 28 receive the displaced material 92, 94 and reduce the forces exerted on the lower substrate 12 in the area of ​​the pre-formed button 18. By pre-forming the button 18, any tendency of the button 18 to break or split is significantly reduced.

[0029] In the case where the lower base plate 12 has a pre-formed outer contour, the lower base plate 12 can be made of a brittle material. Therefore, a brittle material or a low-strain material can be easily joined to another material by a self-piercing rivet.

[0030] A joined composite material or assembly 10 constructed in accordance with the teachings of the present application may be used in automobiles to form body and closure components or in any application requiring the joining of two or more layers of material.

[0031] It should be noted that the present disclosure is not limited to the embodiments described and shown as examples. Various modifications have been described, and more are part of what is known to those skilled in the art. These and other modifications and any replacement by technical equivalents may be added to the specification and drawings without departing from the scope of protection of the present disclosure and this patent.

[0032] According to the present invention, an assembly is provided having: an upper base plate; a lower base plate defining a preformed interior cavity and a preformed exterior contour adjacent to the interior cavity, thereby defining a variable thickness wall; and a self-piercing rivet extending through the upper base plate and into the preformed interior cavity of the lower base plate.

[0033] According to one embodiment, the above invention is further characterized in that the pre-formed internal cavity of the lower base plate does not undergo plastic deformation after the self-piercing rivet is installed.

[0034] According to one embodiment, the above invention is further characterized in that the preformed internal cavity of the lower base plate is plastically deformed after the self-piercing rivet is installed.

[0035] According to one embodiment, the above invention is further characterized in that the lower base plate is an aluminum casting or an aluminum extrusion.

[0036] According to one embodiment, the above invention is further characterized in that the lower substrate is a composite material.

[0037] According to one embodiment, the above invention is further characterized by the pre-formed internal cavity defining a circular groove having a raised central area.

[0038] According to one embodiment, the above invention is further characterized in that the preformed outer contour defines a closed cylinder.

[0039] According to one embodiment, the above invention is further characterized in that the pre-formed outer contour further defines a rounded area extending between the lower surface of the lower base plate and the cylinder.

[0040] According to one embodiment, the above invention is further characterized in that the preformed internal cavity is configured to guide the expansion of the self-piercing rivet.

[0041] According to the present invention, a dimpled substrate for use in an assembly having joined substrates, the dimpled substrate defining at least one preformed interior cavity and at least one preformed exterior contour adjacent the interior cavity, thereby defining a variable thickness wall, wherein the preformed interior cavity is configured to receive a fastening system that plastically deforms at least one of the substrates during joining.

[0042] According to one embodiment, the above invention is further characterized by the pitted substrate defining a plurality of pre-formed internal cavities and a corresponding plurality of pre-formed external contours, the plurality of pre-formed internal cavities being evenly spaced.

[0043] According to one embodiment, the above invention is further characterized in that the lower base plate is an aluminum casting or an aluminum extrusion.

[0044] According to one embodiment, the above invention is further characterized in that the lower substrate is a composite material.

[0045] According to one embodiment, the above invention is further characterized by the pre-formed internal cavity defining a circular groove having a raised central area.

[0046] According to one embodiment, the above invention is further characterized in that the preformed outer contour defines a closed cylinder.

[0047] According to the present invention, an assembly is provided, comprising: an upper base plate; a lower base plate defining a plurality of preformed internal cavities and a corresponding plurality of preformed external contours adjacent the internal cavities, thereby defining a variable thickness wall therebetween; and a plurality of self-piercing rivets extending through the upper base plate and into the preformed internal cavities of the lower base plate, wherein the preformed internal cavities are configured to guide the outward expansion of the self-piercing rivets.

[0048] According to one embodiment, the above invention is further characterized in that the lower base plate is an aluminum casting or an aluminum extrusion.

[0049] According to one embodiment, the above invention is further characterized in that the lower substrate is a composite material.

[0050] According to one embodiment, the above invention is further characterized in that the preformed outer contour defines a closed cylinder.

[0051] According to the invention, there is provided a motor vehicle having an assembly as described above.

Claims

1. A joint assembly, comprising: upper base plate; a lower substrate having a front side facing the upper substrate and a rear side opposite the front side, the front side defining at least one preformed interior cavity, the rear side defining at least one preformed exterior contour adjacent to the at least one preformed interior cavity, the preformed exterior contour cooperating with the preformed interior cavity to define a variable thickness wall; as well as at least one self-piercing rivet extending through the upper base plate and into the at least one pre-formed interior cavity of the lower base plate, The preformed internal cavity defines a circular groove and a central region of a projection, such that before the self-piercing rivet is installed, the variable thickness wall has a greater thickness at the central region of the projection than at the circular groove.

2. The assembly of claim 1 wherein said at least one pre-formed interior cavity of said lower base plate does not plastically deform after said self-piercing rivet is installed.

3. The assembly of claim 1 wherein said at least one pre-formed interior cavity of said lower base plate is plastically deformed after said self-piercing rivet is installed.

4. The assembly of any one of claims 1 to 3, wherein the lower base plate is an aluminum casting or an aluminum extrusion.

5. The assembly of any one of claims 1 to 3, wherein the lower substrate is a composite material.

6. The assembly of claim 1 wherein said circular groove surrounds a central region of said protrusion. 7 . The assembly of claim 6 , wherein the raised central region defines a top surface that is raised to a height above the lower surface of the lower substrate.

8. The assembly of claim 6, wherein the raised central region defines a top surface that is lower than a lower surface of the lower substrate.

9. The assembly of any one of claims 1 to 3, wherein the at least one pre-formed outer contour defines a closed cylinder.

10. The assembly of claim 9, wherein the at least one pre-formed outer contour further defines a radiused region extending between a lower surface of the lower base plate and the barrel.

11. The assembly of any one of claims 1 to 3, wherein the at least one pre-formed internal cavity is configured to guide outward expansion of the self-piercing rivet.

12. The assembly of claim 1, wherein the lower base plate defines a plurality of pre-formed interior cavities and a corresponding plurality of pre-formed exterior contours, the plurality of pre-formed interior cavities being evenly spaced. 13 . The assembly of claim 12 , wherein a central region of the protrusion defines a top surface that is protruded to a height higher than a lower surface of the lower substrate, or defines a top surface that is lower than the lower surface of the lower substrate.

14. An assembly according to claim 12 or 13, wherein each pre-formed outer contour defines a closed cylinder and a rounded region extending between the lower surface of the lower base plate and the cylinder.

15. A motor vehicle having a coupling assembly according to any one of claims 1 to 3.

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