Semi-hollow punch rivet, a punch rivet joint of at least two components by means of a semi-hollow punch rivet as well as a method for connecting the components with the semi-hollow punch rivet

Abstract

A semi-hollow punch rivet by which a joint is establishable. The rivet includes: a rivet head having a rivet shaft, which comprises a lateral surface, a rivet foot having a foot front surface is provided at an end of the rivet shaft facing away from the rivet head, the foot front surface is perpendicular to a longitudinal axis L.sub.A of the rivet shaft, and a bell-like shaft cavity extends into the rivet shaft beginning at the end facing away from the head. The shaft cavity is formed by: an inlet portion beginning at a radial inner side of the foot front surface and extending arc-shaped with an inlet radius R.sub.S in the direction of the rivet head, a linearly extending continuation portion into which the inlet portion transitions tangentially and which is arranged in an acute angle with respect to the lateral surface, and a final dome portion.

Claims

1. A semi-hollow punch rivet by which a joint between at least two components is establishable which are arranged in a pile above each other, which comprises the following features: a. a rivet head having a rivet shaft extending therefrom, which comprises a cylindrical lateral surface, b. a blunt rivet foot having a rivet foot front surface which is arranged perpendicular to a longitudinal axis L.sub.A of the rivet shaft, wherein said blunt rivet foot is provided at an end of the rivet shaft facing away from the rivet head, and c. a shaft cavity which is bell-shaped in an axial cross-section of the rivet shaft extends into the rivet shaft starting at the end facing away from the head, wherein the bell-shaped shaft cavity is formed by i. a convex inlet portion starting at a radial inner side of the rivet foot front surface and extending circular arc-shaped with an inlet radius R.sub.S in the direction of the rivet head, ii. a linearly extending continuation portion into which the inlet portion transitions tangentially and which is arranged in an acute angle α with respect to the cylindrical lateral surface, and iii. a final dome portion, wherein d. one of the following is used as rivet material: steel, or copper.

2. The semi-hollow punch rivet according to claim 1, having a shaft diameter D.sub.a of D.sub.a≤5.6 mm.

3. The semi-hollow punch rivet according to claim 2, wherein the rivet foot front surface has a radially extending foot width B.sub.S in the range of 1/30 D.sub.a≤B.sub.S≤⅓ D.sub.a.

4. The semi-hollow punch rivet according to claim 3, wherein the inlet radius R.sub.S comprises with respect to the foot width B.sub.S the following size: R.sub.S≤20 B.sub.S.

5. The semi-hollow punch rivet according to claim 4, wherein the continuation portion is arranged in the acute angle α in the range of 5°≤α≤30° with respect to the cylindrical lateral surface.

6. The semi-hollow punch rivet according to claim 4, having a depth t.sub.B of the bell shaped shaft cavity with respect to the shaft diameter D.sub.a in the range of ⅓ D.sub.a≤t.sub.B≤⅔ D.sub.a.

7. The semi-hollow punch rivet according to claim 4, wherein the bell shaped shaft cavity comprises a central through opening to the rivet head extending in the longitudinal direction of the rivet shaft or a blind hole to form a hollow rivet.

8. The semi-hollow punch rivet according to claim 3, wherein the continuation portion is arranged in the acute angle α in the range of 5°≤α≤30° with respect to the cylindrical lateral surface.

9. The semi-hollow punch rivet according to claim 3, having a depth t.sub.B of the bell shaped shaft cavity with respect to the shaft diameter D.sub.a in the range of ⅓ D.sub.a≤t.sub.B≤⅔ D.sub.a.

10. The semi-hollow punch rivet according to claim 3, wherein the bell shaped shaft cavity comprises a central through opening to the rivet head extending in the longitudinal direction of the rivet shaft or a blind hole to form a hollow rivet.

11. The semi-hollow punch rivet according to claim 2, wherein the continuation portion is arranged in the acute angle α in the range of 5°≤α≤30° with respect to the cylindrical lateral surface.

12. The semi-hollow punch rivet according to claim 11, having a depth t.sub.B of the bell shaped shaft cavity with respect to the shaft diameter D.sub.a in the range of ⅓ D.sub.a≤t.sub.B≤⅔ D.sub.a.

13. The semi-hollow punch rivet according to claim 11, wherein the bell shaped shaft cavity comprises a central through opening to the rivet head extending in the longitudinal direction of the rivet shaft or a blind hole to form a hollow rivet.

14. The semi-hollow punch rivet according to claim 2, having a depth t.sub.Bof the bell shaped shaft cavity with respect to the shaft diameter D.sub.a in the range of ⅓ D.sub.a≤t.sub.B≤⅔ D.sub.a.

15. The semi-hollow punch rivet according to claim 2, wherein the bell shaped shaft cavity comprises a central through opening to the rivet head extending in the longitudinal direction of the rivet shaft or a blind hole to form a hollow rivet.

16. The semi-hollow punch rivet according to claim 1, wherein the continuation portion is arranged in the acute angle α in the range of 5°≤α≤30° with respect to the cylindrical lateral surface.

17. The semi-hollow punch rivet according to claim 16, wherein the bell shaped shaft cavity comprises a central through opening to the rivet head extending in the longitudinal direction of the rivet shaft or a blind hole to form a hollow rivet.

18. The semi-hollow punch rivet according to claim 1, wherein the bell shaped shaft cavity comprises a central through opening to the rivet head extending in the longitudinal direction of the rivet shaft or a blind hole to form a hollow rivet.

19. A punch rivet joint of at least two components arranged pile-shaped above each other, which are connected to each other by the semi-hollow punch rivet according to claim 1.

20. A method for connecting at least two components by a semi-hollow punch rivet, comprising the following steps: I. providing a semi-hollow punch rivet by which a joint between the at least two components is establishable which are arranged in a pile above each other, which comprises the following features: a. a rivet head having a rivet shaft extending therefrom, which comprises a cylindrical lateral surface, b. a blunt rivet foot having a rivet foot front surface which is arranged perpendicular to a longitudinal axis L.sub.A of the rivet shaft, wherein said blunt rivet foot is provided at an end of the rivet shaft facing away from the rivet head, and c. a shaft cavity which is bell-shaped in an axial cross-section of the rivet shaft extends into the rivet shaft starting at the end facing away from the head, wherein the bell-shaped shaft cavity is formed by i. a convex inlet portion starting at a radial inner side of the rivet foot front surface and extending circular arc-shaped with an inlet radius in the direction of the rivet head, ii. a linearly extending continuation portion into which the inlet portion transitions tangentially and which is arranged in an acute angle a with respect to the cylindrical lateral surface, and iii. a final dome portion, wherein d. one of the following is used as rivet material: steel or copper. II. arranging the at least two components above each other in a pile-shaped arrangement on a die or an anvil and III. setting the semi-hollow punch rivet into the at least two components.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The embodiments of the present disclosure will be described in detail based on the accompanying drawings. Showing:

(2) FIG. 1 a schematic cross-sectional view of an embodiment of the semi-hollow punch rivet with characteristic dimensions for defining the geometry of the semi-hollow punch rivet,

(3) FIG. 2 an enlargement of a section of FIG. 1 in which the consequences of a variation of the size of the inlet radius with respect to the convex inlet portion and thus the variation of the shape of the shaft cavity is shown,

(4) FIG. 3 an enlargement of a section of FIG. 1 in which the shaft cavity and its changed shape due to the variation of the acute angle of the linearly extending continuation portion with respect to the shaping of the shaft cavity and its volume is shown,

(5) FIG. 4 an enlargement of a section of FIG. 1 illustrating a variation of the foot width of the blunt rivet foot of the semi-hollow punch rivet,

(6) FIG. 5 an enlargement of a section of FIG. 1 in which a changed depth of the shaft cavity and the consequences with respect to the volume of the shaft cavity is illustrated,

(7) FIGS. 6a, 6b, 6c and 6d illustrations of designs of the rivet head of the semi-hollow punch rivet,

(8) FIG. 7 a schematic cross-sectional view of the semi-hollow punch rivet with through opening from the shaft cavity to the rivet head for forming a hollow rivet and

(9) FIG. 8 a schematic cross-sectional view of a punch rivet joint with two components,

(10) FIG. 9 a schematic cross-sectional view of a punch rivet joint with three components, and

(11) FIG. 10 a flowchart of an embodiment of the connecting method with the aid of the semi-hollow punch rivet.

DETAILED DESCRIPTION

(12) An embodiment of the semi-hollow punch rivet 1 is shown in FIG. 1. FIG. 1 is a schematical cross-sectional view transverse to the longitudinal axis L.sub.A of the semi-hollow punch rivet 1.

(13) The semi-hollow punch rivet 1 comprises a rivet head 10 with a rivet shaft 30 extending therefrom. The rivet head 10 has depending on the case of application a head shape as they are exemplarily shown in FIG. 6. Accordingly, the rivet shaft 30 may be combined with a countersunk head (FIG. 6A), a countersunk head with arc-shaped transition to the rivet shaft 30 (FIG. 6B) or a flat-round head (FIG. 6C). It may also be preferred to combine the rivet head 10 with a functional element 12 as for example a threaded bolt or a nut (FIG. 6D).

(14) The rivet shaft 30 comprises opposite to the rivet head 10 a blunt rivet foot 40. The rivet foot 40 comprises the rivet foot front surface 42. The rivet foot front surface 42 may be arranged perpendicular to a cylindrical lateral surface 32 of the rivet shaft 30. In the same manner, the rivet foot front surface 42 extends perpendicular to the longitudinal axis L.sub.A of the semi-hollow punch rivet 1.

(15) Starting at the rivet foot 40 a shaft cavity 50 extends in the direction of the rivet head 10 in the interior of the rivet shaft 30. The shaft cavity 50 is arranged rotationally symmetrically around the longitudinal axis L.sub.A of the semi-hollow punch rivet 1.

(16) As can be seen based on the cross-sectional illustration along the longitudinal axis L.sub.A in FIG. 1, the shaft cavity 50 has a bell-like design with an opening adjacent to the rivet foot 40.

(17) The shaft cavity 50 in the rivet shaft 30 may be formed such that besides a sufficient stability of the rivet foot 40 at high punch forces also a sufficiently large receiving volume for the punch slug in the shaft cavity 50 results. In this context, the rivet shaft 30 may be formed as solid element beginning at the rivet head 10.

(18) The rivet shaft 30 provided as solid element extends according to one embodiment at least up to the middle of the semi-hollow punch rivet 1 with an overall length L. In this way, an extensive distribution of the joining force or the punch force in the head near portion of the semi hollow punch rivet 1 may be ensured. This punch force is first of all transmitted over the complete cross-sectional face of the rivet shaft 30 in the direction of the rivet foot 40. The share of the solid element at the rivet shaft 30 is defined by the depth of the shaft cavity 50 as it is explained below.

(19) Due to the shaft cavity 50, the rivet shaft 30 is formed hollow in the foot portion. The shaft cavity 50 extends in a central symmetrical arrangement around the longitudinal axis L.sub.A in the direction of the rivet head 10. A depth t.sub.B of the shaft cavity 50 is chosen such that the semi-hollow punch rivet 1 is deformed during the setting process only in the lower half of the rivet shaft 30, thus in the half of the rivet shaft 30 adjacent to the rivet foot 40. Thus, the geometry of the shaft cavity 50 explained in detail below ensures also a sufficient spreading of the hollow shaft section for forming an undercut in the produced punch rivet joint. This is exemplarily shown in the schematic illustrations of the punch rivet joints of FIGS. 8 and 9.

(20) In a further embodiment of the semi-hollow punch rivet 1, it has a shaft diameter D.sub.a of D.sub.a≤5.6 mm. The shaft diameter D.sub.a may be equal to 5.5 mm so that the semi hollow punch rivet 1 is processable with common punch rivet systems and supply systems.

(21) In this context, the rivet head 10 may be manufactured with a head diameter D.sub.k equal to 7.75 mm. This default size ensures the usage of known joining systems and rivet supply systems.

(22) According to a further embodiment it may also be preferred to combine the above described geometry of the semi-hollow punch rivet 1 with other shaft diameters D.sub.a and/or head diameters D.sub.k.

(23) Further the rivet length L of the semi-hollow punch rivet 1 may be in the range of 4 mm≤L≤9 mm. Depending on the case of application, the rivet length L is adapted to the joining connection or joint to be produced or the pile thickness of the components to be connected to each other.

(24) For being able to realize different joining tasks, the semi-hollow punch rivet 1 may be manufacturable from different materials. The rivet materials may be steel, aluminum or copper. Here, also further materials may be preferred to realize respective joining tasks.

(25) As can be seen based on the illustration of the shaft cavity 50 in FIG. 1, a convex inlet portion 52 begins at the radial inner edge of the rivet foot 40. The convex inlet portion 52 extends arc-shaped in the direction of the rivet head 10.

(26) The arc-shaped inlet portion 52 has according to an embodiment a radius R.sub.S which is defined depending on the foot width B.sub.S of the rivet foot 40. The radially extending foot width B.sub.S of the rivet foot front surface 42 may be in the range of 1/30 D.sub.a≤B.sub.S≤⅓ D.sub.a, wherein D.sub.a describes the above discussed shaft diameter. The foot width B.sub.S may be in the range of 1/15 D.sub.a≤B.sub.S≤⅙ D.sub.a.

(27) A schematic illustration of the variation of the foot width B.sub.S is shown in FIG. 4. It is made clear how the increasing foot width B.sub.S has as a consequence a strengthening of the rivet foot 40. It may also be made clear that an increasing of the foot width B.sub.S leads to a decreasing of the receiving volume of the shaft cavity 50.

(28) The lower limit of the given greater range for the rivet foot width B.sub.S ensures that the rivet foot 40 spreads only after penetrating the cover layer or of a first component in a pile of components. Due to this, a larger undercut formation in the punch rivet joint is ensured which supports the connection of the components.

(29) The stiffness of the rivet foot 40 increases with increasing foot width B.sub.S. Accordingly, with increasing foot width B.sub.S the deformation of the rivet foot 40 or the spreading of the rivet foot 40 is restricted or made difficult. In this context, it has been recognized as advantageous not to extend the foot width B.sub.S beyond the above given upper limit to provide a still sufficient foot deformation and a sufficient large receiving volume for the punch slug in the shaft cavity 50.

(30) Based thereon, the inlet radius R.sub.S may be defined as a multiple of the foot width B.sub.S, especially according to R.sub.S≤20 B.sub.S. Further the inlet radius R.sub.S may have a size of 0.3 mm≤R.sub.S≤6 mm or 1 mm≤R.sub.S≤4 mm. A variation of the inlet radius R.sub.S is schematically shown in FIG. 2.

(31) The convex inlet portion 52 in the radii range makes a flowing widening of the rivet foot 40 during a joining process possible. The flowing widening of the rivet foot 40 may be also connected to a flowing rising of a punch slug into the shaft cavity 50. This is especially advantageous in case ductile material, for example aluminum, as cover layer is combined with a press-hard steel as second layer or as middle layer in a pile of components and in a punch rivet joint provided therein (see FIGS. 8 and 9).

(32) When exceeding the upper limit of the given range of the inlet radius R.sub.S, the inlet portion 52 may comprise a curvature which is too small. Accordingly, the inlet portion 52 has an almost linear course so that the effect of the flowing widening gets lost.

(33) If the inlet radius R.sub.S according to the lower limit with less than 0.3 mm is chosen to small, a sharp-edged inlet portion prevents a flowing widening and entering (see above). Accordingly, it may further be preferred to provide the inlet radius R.sub.S in the range of 1 mm≤R.sub.S≤4 mm.

(34) The convex inlet portion 52 transitions tangentially into the linearly extending continuation portion 54. The continuation portion 54 is formed similar to a lateral surface of a truncated cone which may follow directly behind the inlet portion 52.

(35) The linearly extending continuation portion 54 may be arranged in an acute angle α (see FIG. 1) with respect to the cylindrical lateral surface 32 of the rivet shaft 30. According to different embodiments, the continuation portion 54 may be arranged in an angle α in the range of 5°≤α≤30°, or 5°≤α≤20°.

(36) The acute angle α of the continuation portion 54 has influence on the rigidity of the rivet foot 40 and the formation of an undercut associated therewith in a joining connection. In this regard, an angle α>30° prevents a sufficient spreading of the rivet foot 40. Further, due to this large angle, the shaft cavity 50 would be reduced too much for a punch slug receiving.

(37) The influence of a change of the angle α is schematically shown in FIG. 3.

(38) According to a further embodiment, the shaft cavity 50 has a depth t.sub.B. The depth t.sub.B is defined as the distance between the rivet foot front surface 42 and a point of a dome section 56 which is nearest to the rivet head 10.

(39) The depth t.sub.B may be in the range of ⅓ D.sub.a≤t.sub.B≤⅔ D.sub.a. The depth t.sub.B defines the size of the receiving volume for a punch slug in the shaft cavity 50. Thus, according to a further embodiment, the depth t.sub.B is chosen as large as possible. In this context it has to be noted that with increasing depth t.sub.B of the shaft cavity 50 also the rigidity of the semi-hollow punch rivet 1 is decreased in the foot portion 40.

(40) The above given range is chosen such that at least sheet thicknesses of up to 1.2 mm can be received as punch slug in the shaft cavity 50.

(41) In FIG. 7, the embodiment of the semi-hollow punch rivet 1 with a through opening 60 is shown. The through opening 60 connects the shaft cavity 50 to the upper side of the rivet head 10. Thus, a hollow rivet may be provided in which the through opening 60 additionally makes the receiving and a rising of the material of a punch slug possible.

(42) FIG. 10 shows a flowchart of a connection method of at least two components by means of the above described semi-hollow punch rivet 1. In a first step S1, the at least two components B1, B2 are arranged above each other in a pile-shaped arrangement on a die or an anvil. In a subsequent second step, a setting of the semi-hollow punch rivet 1 into the pile of components is performed to connect the components B1, B2 to each other.

(43) Correspondingly, a punch rivet joint of at least two components B1, B2, B3 is provided which are connected to each other in a pile-shaped arrangement by means of the above described semi-hollow punch rivet 1. An exemplary illustration of a produced punch rivet joint is shown in each of FIGS. 8 and 9. In FIG. 8, the semi-hollow punch rivet 1 connects the two components B1 and B2. In FIG. 9, three components B1, B2, B3 of a pile of components are connected to each other via the semi-hollow punch rivet 1. While in both punch rivet joints a part of the punched out material is at least partly received in the shaft cavity 50, a closing head may have been formed opposite to the rivet head 10.