Semi-hollow self-pierce rivet, manufacturing method thereof, and connection thereof

Abstract

To provide a semi-hollow self-pierce rivet suitable for connecting a multi-layered sheet stack with a thickness.SOLUTION: A semi-hollow self-pierce rivet 1 which can establish a connection between at least two components provided in a stacking manner without a punch hole in advance, is provided with a flush head. In order to advantageously control an expanding behavior of a rivet shaft 30 during a bonding process, a size of a chamfer part 56 in a radial outer side is applied. For this purpose, a rivet leg part 50 includes a geometric shape for preventing the rivet shaft 30 from being expanding at an early stage at an end part opposite to a rivet head part 10, the rivet leg part 50 in which an axial height of the chamfer part 56 in the radial outer side, which is a height of an outer chamfer part, is preferably increased according to a predefined function as an entire length of the semi-hollow self-pierce rivet 1 increases.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a semi-tubular / semi-hollow self-piercing rivet that can establish a connection between at least two components arranged in a stack without pre-punching holes. Furthermore, the present invention relates to the connection of at least two metal components arranged in a stack, which are connected to each other using a semi-hollow self-piercing rivet. Furthermore, the present invention relates to a method for manufacturing said semi-hollow self-piercing rivet by cold forming. [Background technology]

[0002] In the state of the art, there are several different rivet geometries, each with its own structural features directed towards achieving a specific technical function or goal in the self-piercing riveted connection.

[0003] EP2080915A2 discloses a relatively short, 6.5 mm long, semi-hollow self-piercing rivet that is useful for connecting a high-strength steel cover sheet to an aluminum sheet placed underneath.

[0004] The semi-hollow self-piercing rivet in DE102014201976A1 is intended for the same connection of a high-strength steel cover sheet and a thick aluminum layer. Its length is 5.5 mm, and in contrast to EP2080915A2, it does not use a sharp cutting edge on the rivet stem. Rather, despite the same high-strength cover sheet, it uses a flat shaft front whose cutting edge forms the edge of the shaft's radial outer wall. Compared to EP2080915A2, this larger cutting surface requires a higher setting force.

[0005] Due to the short rivet length, these semi-hollow self-piercing rivets are not suitable for connecting taller sheet stacks.

[0006] A similar short semi-hollow self-piercing rivet is disclosed in WO2011 / 023616A1. Its limited length of 4.5mm limits the number or thickness of components to be connected. Furthermore, the shaft borehole has a too small receiving volume to accommodate higher metal sheet thicknesses.

[0007] In addition to the semi-hollow self-piercing rivets disclosed in the above documents, WO 2023 / 057736 A1 also describes a hollow rivet with a total length of up to 11 mm, in addition to a semi-hollow self-piercing rivet with a total length of 6 mm. This hollow rivet has an open-top receiving volume in its shaft, but at the same time, it cannot guarantee a sealed connection. Furthermore, this hollow rivet lacks the stable bridging effect of the rivet head. The same applies to the hollow rivet in WO 2014 / 013232.

[0008] EP3626982B1 discloses a semi-hollow self-piercing rivet for stacks of thick brittle materials. Accordingly, this semi-hollow self-piercing rivet has a length in the range of 11 to 12 mm. At the same time, the axial head thickness is too thick, at 1.5 to 3.5 mm, resulting in a loss of some of the bore volume for receiving the punch slug. Furthermore, the shape of the rivet head and rivet legs is adapted to join brittle materials. The countersunk head transitions from the underside of the head to the radially outer wall of the shaft in a generally arc-shaped fashion, minimizing the increase in shaft diameter during the transition to the countersunk head. This reduces the radial pressure of the countersunk head against the brittle material when the semi-hollow self-piercing rivet is set and the countersunk head is pressed into the cover sheet. The radially outer side of the rivet leg geometry is arc-shaped in a mechanically relaxed manner, similar to the countersunk head geometry, facilitating radially outward sliding of the component materials. The easier or simpler sliding of the materials reduces the radially inward pressure of the component materials against the shafts, thus allowing the shafts to expand more easily and earlier during the joining process.

[0009] The drawback is that the expanded rivet shaft often does not fully release the die cavity and is compressed in a damaging manner by the die.

[0010] US2013 / 0336745A1 describes a semi-hollow self-piercing rivet intended for connecting taller stacks of sheets. It has a cylindrical shaft with a length of 10 mm, followed by a rivet head with an axial head thickness of 2.5 mm. The rivet head stabilizes the rivet shaft on the one hand, but also partially obstructs the shaft's additional receiving volume. Therefore, this semi-hollow self-piercing rivet lacks effective space utilization in its structure.

[0011] EP3287210A2 discloses a further semi-hollow self-piercing rivet. It features a circular shaft terminating in a rivet head. The rivet head includes a cylindrical head plate that axially closes the semi-hollow self-piercing rivet and extends radially beyond the shaft. The side of the head plate facing the shaft transitions tangentially to the outside of the shaft in an arc. On the side of the head plate facing the shaft, the arcuate connection to the shaft begins only between the radially outer side of the shaft and the head. This allows the semi-hollow self-piercing rivet to be set relatively deeply, but because the shaft expands radially toward the rivet head or head plate, the shaft absorbs only a small amount of joining energy. The disadvantage of this is that the semi-hollow self-piercing rivet is set too deep.

[0012] DE 10 2021 133 544 A1 describes a semi-hollow self-piercing rivet whose overall length makes it suitable for joining taller stacks of sheets. To stabilize the shaft of the semi-hollow self-piercing rivet for such joining operations, the radial thickness of the shaft's peripheral wall increases in the axial direction of the rivet shaft. However, this advantageous stabilization also leads to a reduction in the receiving volume of the shaft borehole for receiving the punch slug. This limited receiving volume can create negative pressure tension in the shaft, which can have a detrimental effect on the joining process.

[0013] Therefore, in view of the above-mentioned state of the art, it is an object of the present invention to provide a further improved semi-hollow self-piercing rivet suitable for connecting thick multi-layer sheet stacks. Summary of the Invention

[0014] The above problem is solved by a semi-hollow self-piercing rivet according to independent claim 1, a self-piercing rivet connection according to independent claim 9, and a method for manufacturing a self-piercing rivet according to independent claim 10. Advantageous embodiments and further developments will become apparent from the following description, the drawings, and the appended claims.

[0015] The present invention relates to a semi-hollow self-piercing rivet capable of establishing a connection between at least two components arranged in a stack without pre-punching holes, the rivet comprising an axially closing rivet head, a rivet shaft extending from the rivet head, a rivet leg geometry at the end of the rivet shaft facing away from the rivet head, and a total length L of the semi-hollow self-piercing rivet in the range of 7 mm≦L≦16 mm, the rivet head being 7.5 mm≦D K Head diameter D in the range of ≦7.9 mm K When viewed in axial cross section, the rivet has a countersunk shape with a cylindrical section starting axially on the radially outer side, a frustoconical section following the cylindrical section, and an arcuate section following the frustoconical section that transitions tangentially to the rivet shaft, the rivet shaft having a hollow cylindrical shape and an outer shaft diameter DS is 5.2mm≦D S ≦5.6mm, and the borehole diameter D B is 3.1mm≦D B ≦3.5 mm, and therefore the head diameter D K Borehole diameter D S The ratio is 0.39≦D B / D K ≦0.5, and the borehole depth T B is 6mm≦T B ≦15mm, and therefore the borehole volume V of the rivet shaft B is the total length L of the semi-hollow self-pierce rivet. B min ≦V B ≦V B max where V B min =7.3 [mm 2 ]·L [mm], and V B max =9.0 [mm 2 ]·L [mm], and in axial cross section, the rivet leg has a conical radial outer chamfer and a conical inner chamfer interconnected by a cutting edge, the conical inner chamfer transitioning tangentially to the radial inner bore wall of the shaft via an arc section, and the outer chamfer and the inner chamfer are 80°≦W S Cutting angle W in the range of ≦90° S A semi-hollow self-pierce rivet is disclosed, which has the following characteristics:

[0016] The present invention provides a semi-hollow self-piercing rivet with a long overall length, i.e., a length significantly longer than that of known semi-hollow self-piercing rivets with a length of 5 mm or 6 mm. This long overall length meets the requirements for connecting large stacks of several sheets arranged one on top of the other, or at least two sheets of a certain thickness. Furthermore, the combination of the overall length of this semi-hollow self-piercing rivet and the deep cylindrical shaft borehole ensures sufficient receiving volume for the punch slug rise of the components to be connected together.

[0017] For this purpose, the semi-hollow self-piercing rivet of the present invention is intentionally provided with a countersunk head. This countersunk head is created by arranging a cylindrical section, a conical section, and a section of the semi-hollow self-piercing rivet that has a concave or arcuate axial cross section directly in succession in the joining direction. This countersunk head geometry, with its small axial remaining head thickness, maximizes the receiving volume in the shaft borehole. At the same time, the semi-hollow self-piercing rivet is sealed and mechanically stabilized by the countersunk head that closes the shaft borehole.

[0018] The rivet leg features a geometry that prevents premature splaying of the rivet shaft at the end opposite the rivet head, as the conical radially outer chamfer and the conical radially inner chamfer mutually compensate for the pressure of the punch slug entering the shaft borehole and the pressure of the component material surrounding the shaft. To maintain this compensation during the joining process, the conical inner chamfer transitions tangentially to the radially inner wall of the shaft borehole via an arc section. The edgeless arcuate transition allows the punch slug to slide into the shaft bore without frictional interference from the radially inner wall of the shaft borehole.

[0019] According to a first preferred configuration of the semi-hollow self-piercing rivet, the conical radially outer chamfer has a length of H S = 0.032·L [mm], the outer chamfer height H as a function of the total length L of the semi-hollow self-pierce rivet S It has.

[0020] The size of the radial outer chamfer is adapted to allow for desirable control of the rivet shaft spreading behavior during the joining process. To this end, as the total length of the semi-hollow self-pierce rivet increases, the axial height of the radial outer chamfer, i.e., the outer chamfer height, preferably increases according to a given function. To this end, the total length L, in millimeters, is entered into the function.

[0021] As the outer chamfer height increases, the surface area of ​​the outer chamfer that engages the component material also increases. The outer chamfer surface area alone stabilizes the rivet shaft against expansion due to punch slug lift, as the component material favorably resists radially outward material displacement during the joining process.

[0022] The outer chamfer of the cone in the radial direction is 0.15 mm or less. S Radial outer chamfer width B in the range of ≦0.35 mm S It is also preferred that the

[0023] To further favorably control the rivet shaft spreading behavior, the surface area of ​​the radially outer chamfer at the rivet foot is determined by the radially outer chamfer width, which is preferably measured between the cutting edge and the cylindrical radially outer surface of the rivet shaft, which extends to the axial height of the cutting edge. By selecting the outer chamfer width from a given range, the surface area of ​​the outer chamfer can be adapted to control the rivet shaft spreading behavior.

[0024] According to a further preferred embodiment of the semi-hollow self-pierce rivet, the conical radially inner chamfer is followed axially by an arc section having a radius of 0.2 mm≦R S ≦1.1mm, especially 0.5mm≦R S Entrance radius R to shaft borehole ≦1 mm S It has.

[0025] The cutting edge of the rivet leg determines the approximate diameter of the slug that will be received within the shaft borehole when the semi-hollow self-pierce rivet is set into at least two components. Setting tests have shown that the punch slug displacing into the shaft borehole is often blocked, or at least its movement into the shaft borehole is stopped or slowed, by a corner or edge on the radially inner wall of the shaft borehole. To avoid such an edge or corner, which is typically found where the conical radially inner chamfer terminates at the radially inner wall of the shaft borehole, the conical inner chamfer preferably transitions tangentially to the radially inner wall of the shaft borehole in an arcuate manner.

[0026] Preferably, the inlet radius R S Outer chamfer height H S The ratio is 0.2≦H S / R S The range is ≦1.2.

[0027] When a semi-hollow self-piercing rivet is inserted into at least two stacked components in the joining direction, different radial forces are applied to the peripheral wall of the rivet shaft. Thus, a radially outward pressure is generated by the punch slug rising in the shaft borehole toward the rivet head. Furthermore, a radially inward pressure is generated by the component material that engages and displaces on the radially outer side. A favorable approximate balance between these opposing radial pressures and / or favorable limitations on these pressures allows for a reliable joining process. To ensure this reliable joining process, the aforementioned relationship between the outer chamfer height and the entrance radius of the arcuate section of the radially inner chamfer has been recognized as an important criterion in several tests.

[0028] According to a further preferred embodiment of the semi-hollow self-piercing rivet based on the first configuration or in combination with this first configuration, the head diameter D K Shaft diameter D S The ratio of D is 0.5≦D S / DK The range is ≦0.75.

[0029] The rivet head has a larger diameter than the rivet shaft so that the rivet head exerts sufficient retention on the punch slug of the component to complete the joining process without penetrating the component unduly deep. Preferably, the head diameter exceeds the shaft diameter by 25% to 50% of the shaft diameter. Thus, the head diameter preferably exceeds the shaft diameter by one-quarter or two times its size.

[0030] According to the invention, the axially closing rivet head is H K1 = 0.1·L [mm] - 0.1 mm, the minimum axial head thickness H according to the total length L of the semi-hollow self-pierce rivet K1 , i.e., the axial head thickness of the semi-hollow self-pierce rivet.

[0031] For example, it has been found that, compared to hollow rivets, a closing rivet head provides additional stability to the rivet shaft. Furthermore, the rivet head prevents the punch slug from rising too far above the surface of the component. To avoid rivet head cracks due to mechanical tensions caused by punch slug rise, the rivet head has a preferred head thickness H, which is defined as a function of the overall length of the semi-hollow self-piercing rivet according to the formula above. K1 As the overall length of the semi-hollow self-piercing rivet increases, the size of the slug that can be accommodated also increases. The associated higher mechanical load on the rivet head is preferably compensated for by an axial thickness of the rivet head adapted to its overall length.

[0032] According to a further preferred configuration of the semi-hollow self-piercing rivet in combination with the previous embodiment, the semi-hollow self-piercing rivet has an overall length L in the range 10.5 mm≦L≦16 mm.

[0033] It has been recognized that the preferred semi-hollow self-pierce rivet of the present invention exhibits particularly reliable connection characteristics, particularly in the 10.5 mm to 16 mm portion of its overall length.

[0034] Furthermore, the present invention discloses the connection of at least two metal components arranged one above the other in a stack, which are connected to each other using a semi-hollow self-piercing rivet according to at least one of the aforementioned configurations.

[0035] Furthermore, the present invention discloses a method for manufacturing a semi-hollow self-piercing rivet, which includes the steps of providing a wire material and cold-forming a semi-hollow self-piercing rivet having at least one of the geometric configurations described above.

[0036] The method for manufacturing a semi-hollow self-piercing rivet of the present invention is based on the known method for cold-forming semi-hollow self-piercing rivets from wire material, and the tool used for this purpose is adapted to the structural features of the semi-hollow self-piercing rivet described above in order to achieve the corresponding results, i.e., the advantageous structural features of the semi-hollow self-piercing rivet.

[0037] The manufacturing method includes the further preferred steps of applying a corrosion protection layer to the surface of the cold-formed semi-hollow self-pierce rivet and / or applying a liquid coating to reduce the coefficient of friction on the surface of the semi-hollow self-pierce rivet.

[0038] To support the aforementioned positive structural features regarding lifespan, a corrosion protection layer is additionally applied to the cold-formed semi-hollow self-pierce rivet. Alternatively or in addition, the surface of the semi-hollow self-pierce rivet is coated to reduce the friction that occurs when contacting the semi-hollow self-pierce rivet. In this way, setting the semi-hollow self-pierce rivet is made easier and the associated labor is reduced.

[0039] A preferred embodiment of the present invention will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a schematic cross-sectional view of a preferred embodiment of the semi-hollow self-pierce rivet of the present invention. [Figure 2] FIG. 2 is a further schematic cross-sectional view with dimensioned symbols of a preferred embodiment of the semi-hollow self-pierce rivet of the present invention. [Figure 3] 1 is a schematic diagram of the connection of at least two components arranged in a stacked manner using a preferred semi-hollow self-piercing rivet of the present invention. [Figure 4] 1 is a flowchart of a preferred embodiment of a method for manufacturing a semi-hollow self-pierce rivet according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0041] Figure 1 shows a schematic diagram of a preferred embodiment of the semi-hollow self-piercing rivet 1 of the present invention. At least two sheet layers arranged one on top of the other can be connected using the semi-hollow self-piercing rivet 1. Such a connection between components B using the semi-hollow self-piercing rivet 1 is shown in Figure 3. According to a preferred embodiment of the present invention, at least one component B is made of aluminum or an aluminum alloy.

[0042] The semi-hollow self-piercing rivet 1 comprises a rivet head 10 that closes in the axial direction, a rivet shaft 30 that extends from the rivet head 10, and a rivet leg 50 that axially terminates the rivet shaft 30. The axial direction of the semi-hollow self-piercing rivet 1 is indicated by the dashed central vertical axis l in Figure 1.

[0043] The axially closed rivet head 10 prevents contaminants and moisture from penetrating the rivet shaft 30, thus protecting the established component B connection from corrosion.

[0044] The semi-hollow self-pierce rivet 1 has a total length L in the range of 7 mm≦L≦16 mm.

[0045] The rivet head 10 has a diameter of 7.5 mm or less. K Head diameter D in the range of ≦7.9 mm K It has.

[0046] Furthermore, the rivet head has a countersunk head shape. F At the end of the semi-hollow self-piercing rivet 1 facing away from the rivet stem 50, the rivet head 10 has a cylindrical section 12 with a cylindrical side surface. F At the center is a conical section 14. The conical section 14 preferably defines a cone angle K in the range 120°≦K≦160°.

[0047] The conical section 14 transitions tangentially to the radially outer side 32 of the rivet shaft 30 in the arcuate section 16 .

[0048] Preferably, the total axial length H of the three sections, the cylindrical section 12, the conical section 14, and the arcuate section 16, is K2 is the preferred axial head thickness H K1 , especially the minimum axial head thickness H K1 is smaller than.

[0049] Minimum axial head thickness H K1 is the total length L of the semi-hollow self-pierce rivet 1 and the borehole depth T of the central shaft borehole 34. B This is the difference between

[0050] Total axial length H K2 Compared to the minimum axial head thickness H K1 is preferably larger because otherwise material ingress can occur at the radially outer portion of the borehole bottom of the central shaft borehole 34 during cold forming or cold forming of the semi-hollow self-pierce rivet 1 from the wire blank, which can lead to mechanical weakening of the semi-hollow self-pierce rivet 1.

[0051] According to a preferred embodiment of the semi-hollow self-piercing rivet 1 of the present invention, the closing rivet head 10 is K1 = 0.1·L [mm] - 0.1 mm, and the axial head thickness H according to the total length L of the semi-hollow self-pierce rivet 1 K1 For application of the above formula, the total length L is given in millimeters as shown in square brackets.

[0052] According to a preferred embodiment of the semi-hollow self-pierce rivet 1 of the present invention, the minimum axial head thickness H K1 0.9mm≦H K1 The range is ≦3.1 mm.

[0053] The rivet shaft 30 has a hollow cylindrical shape as can be seen in the schematic cross-sectional views of Figures 1 and 2. The hollow cylindrical rivet shaft 30 has a diameter of 5.2 mm or less. S Outer diameter D in the range of ≦5.6 mm S It has.

[0054] Shaft borehole 34: 3.1 mm ≤ D B Borehole diameter D in the range of ≦3.5mm B Furthermore, the shaft borehole 34 has a diameter of 6 mm or less. B Borehole depth T in the range of ≦15 mm B In this case, the borehole depth T B is preferably measured along the central longitudinal axis l. Thus, the semi-hollow self-pierce rivet 1 has a borehole depth T relative to the total length L of the semi-hollow self-pierce rivet in the range of 0.7 to 0.95. B The preferred ratio is:

[0055] The primary function of the deep borehole is to capture the material displaced from component B. The high material capture reduces the die volume required and allows a lower die height to be used to create the punch rivet connection.

[0056] Additionally, insufficient uptake of component material into the rivet borehole 34 can result in accumulation of component material in front of the rivet blade 52 during the joining process, reducing the cutting characteristics (see below) of the rivet leg 50 and potentially leading to clinching of the blade.

[0057] Therefore, the semi-hollow self-piercing rivet 1 of the present invention has a length V according to the total length L of the semi-hollow self-piercing rivet 1. B min ≦V B ≦V B max Borehole volume V of rivet shaft 30 in the range B where V B min =7.3mm 2 L [mm] and V B max =9.0mm 2 ·L [mm].

[0058] Available borehole volume V B In order to be able to fully capture material in the form of punch slugs within the borehole 34 using the above-defined borehole diameter D of the shaft borehole 34, B In order to prevent the semi-hollow self-piercing rivet 1 from cutting and prematurely deforming at its rivet leg 50 over time during the joining process, a specific wall thickness S of the rivet shaft 30 is required. W The wall thickness S of the rivet shaft 30 is required. W is the formula S W =1 / 2(D S -D B ) where the wall thickness S W is preferably 0.85 mm≦S W The range is ≦1.25 mm.

[0059] Borehole diameter D B and diameter D K Tests have shown that it is advantageous for the quotient of D to be within a certain range, which emphasizes maximizing the intake volume of the shaft borehole 34 while still providing sufficient head stability. Specifically, the head diameter D K Borehole diameter DB The ratio of 0.39≦D B / D K The range is ≦0.5.

[0060] Furthermore, since a rivet shaft 30 with a shaft borehole 34 of this diameter requires a high setting force or setting energy to punch the punch slug and to receive the punch slug into the shaft borehole 34, respectively, the range of the above relationship primarily emphasizes correlation with the effort to set the semi-hollow self-pierce rivet 1.

[0061] The above relationship is secondarily related to the controlled energy consumption during the setting process, since when the setting process is initiated by supplying setting force and energy via the punch of the setting device, the countersunk head 10, which is radially expanded to its head diameter, preferentially converts the supplied setting energy into displacement energy of the constituent material of at least the cover sheet of the component stack. Thus, the determined head diameter D K preferably results in a certain reduction of the setting energy still present.

[0062] The above observations regarding the energy during the joining process, i.e. the interplay between the setting energy supplied to the semi-hollow self-piercing rivet 1 and the energy consumption due to the geometrical characteristics of the semi-hollow self-piercing rivet 1, also preferably take into account the head diameter D K Shaft diameter D S According to a preferred embodiment of the present invention, 0.5≦D S / D K ≦0.75 applies.

[0063] The semi-hollow self-pierce rivet 1 further comprises a rivet leg 50 having a particular rivet leg geometry, preferred details of which are shown in FIGS.

[0064] To be able to join thick and / or multi-layered metal sheet combinations, preferably combinations of related materials, a rivet or cutting blade 52 is required. The cutting blade 52 separates the component materials and creates a punch slug. Furthermore, the cutting blade 52, which is influenced by further structural features directly adjacent to the rivet leg 50, must be able to prevent clinching of the blade due to the separating component materials. For this purpose, the geometry of the rivet leg must be sufficiently stable to prevent premature deformation. Furthermore, this stability ensures that the rivet leg 50 penetrates in the joining direction all the way to the last sheet of component material B to be joined together.

[0065] To achieve the above objective, the cutting edge 52 is formed by a conical radial outer chamfer 54 and a conical radial inner chamfer 56. The outer chamfer 54 and the inner chamfer 56 are linearly configured so as to be directly adjacent to the cutting edge 52 in an axial cross section of the semi-hollow self-piercing rivet 1, and 80°≦W S Preferred cutting angle W in the range of ≦90° S To do.

[0066] The conical radially inner chamfer 56 transitions tangentially to the radially inner bore wall 36 of the rivet shaft 30 via an arc section 58 .

[0067] The conical radially outer chamfer 54, which preferably forms or constitutes an annular surface surrounding the rivet shaft 30, generates pressure that is directed radially inwardly of the rivet leg 50 and therefore the rivet shaft 30 during the joining process. This radially inward pressure against the shaft wall 38 preferably opposes the radially outward pressure of the punch slug entering the rivet shaft 30. Therefore, by specifically tailoring the surface area of ​​the conical radially outer chamfer 54, premature widening of the rivet shaft 30 is prevented.

[0068] To control the surface area of ​​the conical radial outer chamfer 54, the outer chamfer 54 has a preferred outer chamfer height H in the axial cross section of the semi-hollow self-pierce rivet 1. S According to Figure 2, the outer chamfer height H S is measured parallel to the central longitudinal axis l of the semi-hollow self-pierce rivet 1. It is determined by the axial distance between the rivet blade 52 and the point where the conical outer chamfer 54 meets the radially outer flank 32 of the rivet shaft 30.

[0069] Preferably, the outer chamfer height H S is H S = 0.032·L [mm], depending on the total length L of the semi-hollow self-pierce rivet 1.

[0070] The surface area of ​​the outer chamfer 54 is 0.15 mm ≦ B S Radial outer chamfer width B in the range of ≦0.35 mm S It is more preferred that the temperature is further determined by:

[0071] As already mentioned above, the conical radially inner chamfer 56 transitions tangentially to the radially inner wall 36 of the shaft borehole 34 via an arc section 58. The arc section 58 prevents the conical radially inner chamfer 56 and the radially inner wall 36 of the shaft borehole 34 from forming an edge or offset. In practice, it has been found that a punch slug rising within the shaft borehole 34 tends to be blocked or impeded by such an edge or offset during its upward movement.

[0072] According to a preferred embodiment of the present invention, the arc section 58 has a radius of curvature of 0.2 mm≦R S Radius R in the range of ≦1.1 mm S According to a further preferred embodiment of the present invention, the radius R S is 0.5mm≦R S The range is ≦1mm.

[0073] This surface area and radius R SPreferably, the profile of the arc section 58 defined by provides a balanced relationship between the mechanical loads causing the rising slug to spread the rivet shaft 30 and the radially inward force caused by the displaced component material on the conical radially outer chamfer 54.

[0074] According to the present invention, the aforementioned balanced relationship is achieved by the outer chamfer height H S and the inlet radius R S This quotient is preferably in the range of 0.2≦H S / R S The range is ≦1.2.

[0075] The aforementioned geometrical features of the semi-hollow self-piercing rivet 1 preferably have a particularly advantageous effect when the semi-hollow self-piercing rivet 1 has a total length L of 10.5 mm≦L≦16 mm.

[0076] In accordance with a further preferred embodiment of the present invention, a liquid coating is applied to reduce the coefficient of friction on the surface of the semi-hollow self-pierce rivet 1. This preferred coating preferably serves two functions. First, it facilitates the lifting of the punch slug into the shaft borehole 34. The coating also reduces friction on the radially outer flank 32 of the rivet shaft 30, thereby reducing the setting force required for the semi-hollow self-pierce rivet 1.

[0077] In contrast, high friction on the surface of a semi-hollow self-piercing rivet and a slow rise of the punch slug can cause material to accumulate in front of the cutting edge 52, leading to clinching of the blade on the rivet leg 50 and potentially premature widening of the rivet shaft 30 during the joining process.

[0078] Preferably, the coating consists of two components: a base coating for corrosion resistance and a top coat for adjusting frictional properties. The base coating can be applied by electroplating or mechanically. The top coat is applied as a dry-gliding film by liquid coating.

[0079] Furthermore, the present invention includes the connection, as shown diagrammatically in Figure 3, of at least two components B arranged one on top of the other in a stack, which are connected to one another using a semi-hollow self-piercing rivet 1 according to one of the previously described embodiments.

[0080] The present invention further discloses a method for manufacturing a semi-hollow self-piercing rivet 1 according to the flowchart of Figure 4. This method includes the steps of preparing a wire material (S1), cold-forming a semi-hollow self-piercing rivet having at least one of the features described above (step S2), preferably applying an anti-corrosion layer to the cold-formed semi-hollow self-piercing rivet 1 (step S3), and / or preferably applying a liquid coating to reduce the coefficient of friction on the surface of the semi-hollow self-piercing rivet 1 (step S4). [Explanation of symbols]

[0081] 1: Semi-hollow self-piercing rivet 10: Rivet head 12: Cylindrical area 14: Cone area 16: Arc area 30: Rivet shaft 32: Radial outer side 34: Central shaft borehole 36: Inner borehole wall 38: Shaft wall 50: Rivet leg 52: Rivet blade / cutting edge 54: Radial outer chamfer 56: Radial inner chamfer 58: Arc Area B: Components D K : Head diameter R F : Joining direction K: Cone angle H K1 : Minimum axial head thickness T B : borehole depth S W : Wall thickness of the rivet shaft

Claims

1. A semi-hollow self-piercing rivet (1) capable of establishing a connection between at least two components (B) arranged in a stack without pre-punching holes, comprising: a. an axially closing rivet head (10), a rivet shaft (30) extending from the rivet head (10), a rivet leg geometry (50) at the end of the rivet shaft (30) facing away from the rivet head (10), and a total length L of the semi-hollow self-pierce rivet (1) in the range of 7 mm≦L≦16 mm; b. The rivet head (10) has a diameter of 7.5 mm or less. Ｋ Head diameter D in the range of ≦7.9 mm Ｋ and when viewed in axial cross section, has a countersunk shape with a cylindrical section (12) starting axially at the radially outer side, a frustoconical section (14) following said cylindrical section (12), and an arcuate section (16) following said frustoconical section (14) transitioning tangentially to the rivet shaft (30), c. The rivet shaft (30) has a hollow cylindrical shape and an outer diameter D Ｓ is 5.2 mm ≦ D Ｓ ≦5.6 mm, and the borehole diameter D Ｂ is 3.1 mm ≦ D Ｂ ≦3.5 mm, and therefore the head diameter D Ｋ Borehole diameter D Ｓ The ratio is 0.39≦D Ｂ / D Ｋ ≦0.5, and the borehole depth T Ｂ is 6mm≦T Ｂ ≦15 mm, and therefore the borehole volume V of the rivet shaft (30) Ｂ is V according to the total length L of the semi-hollow self-pierce rivet (1). Ｂ ｍｉｎ ≦V Ｂ ≦V Ｂ ｍａｘ where V Ｂ ｍｉｎ = 7.3 [mm ２ ]·L [mm], and V Ｂ ｍａｘ = 9.0 [mm ２ ]·L [mm], d. In axial cross section, the rivet leg (50) has a conical radially outer chamfer (54) and a conical inner chamfer (56) interconnected by a cutting edge (52), the inner conical chamfer (56) transitioning tangentially to the radially inner bore wall (36) of the shaft via an arc section (58), the outer chamfer (54) and the inner chamfer (56) having an angle of 80°≦W Ｓ Cutting angle W in the range of ≦90° Ｓ To do A semi-hollow self-piercing rivet (1) with the following characteristics.

2. The conical radially outer chamfer (54) is H Ｓ = 0.032 L [mm], the outer chamfer height H as a function of the total length L of the semi-hollow self-pierce rivet (1) Ｓ 2. The semi-hollow self-pierce rivet (1) according to claim 1, having:

3. The conical radially outer chamfer (54) has a diameter of 0.15 mm≦B Ｓ Outer chamfer width B in the range of ≦0.35 mm Ｓ 3. The semi-hollow self-pierce rivet (1) according to claim 2, having

4. Axial following the conical radially inner chamfer (56), the arc section (58) has a radius of curvature of 0.2 mm≦R Ｓ Entrance radius R to shaft borehole (34) of ≦1.1 mm Ｓ 4. The semi-hollow self-pierce rivet (1) according to claim 3, having

5. The inlet radius R Ｓ The outer chamfer height H Ｓ The ratio is 0.2≦H Ｓ / R Ｓ 5. The semi-hollow self-pierce rivet (1) according to claim 4, wherein the axial length is in the range of ≦1.

2.

6. The head diameter D Ｋ the shaft diameter D Ｓ The ratio of 0.5≦D Ｓ / D Ｋ 6. The semi-hollow self-pierce rivet (1) according to claim 1, 2, 3, 4 or 5, in the range of ≦0.

75.

7. The axially closing rivet head (10) is H Ｋ１ = 0.1 L - 0.1 mm, the axial head thickness H according to the total length L of the semi-hollow self-pierce rivet (1) Ｋ１ 6. A semi-hollow self-pierce rivet (1) according to claim 1, 2, 3, 4 or 5, having

8. 6. A semi-hollow self-pierce rivet (1) according to any one of claims 1 to 5, having a total length L in the range 10.5 mm≦L≦16 mm.

9. 10. The connection of at least two metal components (B) arranged one above the other in a stack and connected to one another using a semi-hollow self-piercing rivet (1) according to claim 1.

10. A method for manufacturing a semi-hollow self-piercing rivet (1), comprising: a. A step (S1) of preparing a wire material; b) cold-forming (S2) a semi-hollow self-piercing rivet (1) having the features of claim 1; A manufacturing method comprising:

11. c. Applying a corrosion protection layer to the cold-formed semi-hollow self-pierce rivet (1) (S3); The method of claim 10 further comprising:

12. d. Applying a liquid coating to reduce the coefficient of friction on the surface of the semi-hollow self-pierce rivet (1) (S4); The method of claim 10 or 11, further comprising:

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