阅读说明：本技术 自冲铆连接结构以及冲铆钉 (Self-punching rivet connecting structure and punching rivet ) 是由 N·霍恩博斯特尔 H·黑尔迈耶 F·B·巴尔克豪森 于 2020-03-20 设计创作，主要内容包括：本发明涉及一种自冲铆连接结构,其具有至少两个由强度最高为300MPa的能变形的金属材料、尤其是铝质材料制成的构件(1、3),所述构件在一个铆接过程中相互连接,在其中,冲铆钉(5)以设定力(F)穿过凸模侧的第一构件(1)并且钉入凹模侧的第二构件(3)中,确切的说,在第二构件(3)中保留剩余底部厚度(r)的情况下并且在冲铆钉(5)在第二构件(3)中扩张到的扩张直径(d-(A))的情况下。根据本发明,在铆接过程之后,冲铆钉(5)镦缩到其初始长度(l)的60％,并且张开直径(d-(A))增大到铆钉杆直径(d-(S))的140％至150％,但是尤其是铆钉杆直径的140％,而不会由于冲铆材料撕裂损坏冲铆钉(5)。(The invention relates to a self-piercing rivet connection having at least two components (1, 3) made of a deformable metal material, in particular an aluminum material, having a strength of up to 300MPa, which are connected to one another in a riveting process, wherein a piercing rivet (5) is inserted with a setting force (F) through a first component (1) on the male mold side and into a second component (3) on the female mold side, specifically with a residual base thickness (r) remaining in the second component (3) and with an expansion diameter (d) to which the piercing rivet (5) expands in the second component (3) A ) In the case of (1). According to the invention, after the riveting process, the punch rivet (5) is upset to 60% of its initial length (l) and is opened to a diameter (d) A ) Enlarged to rivetNail shank diameter (d) S ) 140% to 150%, but especially 140% of the rivet shank diameter, without damage to the punch rivet (5) due to tearing of the punch rivet material.)

1. A self-piercing rivet connection having at least two components (1, 3) made of a deformable metal material, in particular an aluminum material, having a strength of up to 300MPa, which are connected to one another during the riveting process, wherein a piercing rivet (5) is driven with a setting force (F) through a first component (1) on the male die side and into a second component (3) on the female die side, specifically such that a residual base thickness (r) remains in the second component (3) and the expanding diameter (d) to which the piercing rivet (5) expands in the second component (3) is_A) Characterized in that after the riveting process the punch rivet (5) is headed down to 60% of its initial length (l) and the opening diameter (d)_A) Increase to rivet shank diameter (d)_S) 140% to 150%, in particular 140% of the shank diameter, without damage to the punch rivet (5) by tearing of the punch rivet material.

2. Self-piercing rivet connection according to claim 1, characterized in that the not yet deformed piercing rivet (5) has a cylindrical shank (9) and a specific shank diameter (d)_S) Rivet head (7) with larger diameter, the rivet shank being orientedThe shank tip has an open, in particular truncated-spherical, recess (15), after the riveting process the stamped rivet recess (15) is substantially completely filled with the stamped rivet material due to the material flow during the riveting process, and after the riveting process the shank tip has a substantially flat end face or a rounded end face with an increased radius relative to the rivet size.

3. Self-piercing connecting structure according to claim 1, characterized in that the recess (15) projects axially into the rivet shank (9) starting from the shank tip with a recess depth (t) in the undeformed state, and the recess depth (t) is in particular between 10% and 25% of the total length (L) of the piercing rivet, in particular 15% of the total length of the piercing rivet, and/or a rivet head material thickness (m) extending along the rivet longitudinal axis (L) between the upper rivet head side (17) and the recess (15)_K) Is between 75% and 90% of the total length (l) of the punch rivet, in particular 85% of the total length of the punch rivet.

4. Self-piercing riveted connection according to claim 2 or 3, characterized in that the head radius (r) is constant and is configured by rounding_K) The rivet head underside (16) of (1) forms a transition between the rivet shank (9) and the rivet head (7), in particular the rounded rivet head underside (16) transitions tangentially radially outwards into a gentle, conical rivet head underside which extends to a rivet head edge (19) and/or in particular the planar, conical rivet head underside is inclined at an angle of inclination (alpha) to the horizontal in the direction of the rivet head upper side (17) upwards, and in particular a head radius (r)_K) Between 0.8mm and 2.0mm and/or the inclination angle (a) is in the order of 20 °.

5. Self-piercing rivet connection according to one of the preceding claims, characterized in that the piercing rivet (5) is a flat-head rivet with a planar upper rivet head (17), in which the upper rivet head (17) is flush with the surface of the first component (1) on the punch side, i.e. without a head heightIn the case of the orientation, specifically, the orientation is not particularly convex with respect to the entire component surface, and in particular, the circumferential rivet head edge (19) extends radially outward over a head-side height (l) between the rivet head underside (16) and the rivet head upper side (17)_K) Height of the head side (l)_K) In particular 0.3 mm.

6. A self-piercing rivet connection according to one of the preceding claims, characterized in that an annularly encircling piercing edge (21) which delimits the recess (15) is formed at the shank end facing away from the rivet head (7), and in that the piercing edge (21) serves as a cutting edge during the piercing process, on the one hand, early upsetting of the piercing rivet (5) is prevented by the cutting edge, and on the other hand, the radially outward spreading of the piercing rivet (5) to a predetermined spreading dimension can be controlled, in particular, the wall (23) of the piercing rivet recess (15) and the rivet shank circumference intersect at the piercing edge (21), in particular at an acute edge angle (β) of 45 °, and/or the piercing edge (21) has a fillet radius (r) in the range of 0.15mm_a) Is rounded.

7. Self-piercing rivet connection according to one of the preceding claims, characterized in that the total length (l) of the piercing rivet in the undeformed state is 4mm to 8mm, in particular between 4.5mm and 6.0mm, and the rivet head diameter (d)_K) 4.5mm to 8.5mm, in particular 5.5mm or 7.75mm, and/or the rivet shank diameter (d)_S) 2.8mm to 6.6 mm.

8. Self-piercing rivet connection according to one of the preceding claims, characterized in that the base material of the piercing rivet (5) is a wire made of cold-extruded or cold-forged steel, and/or that the piercing rivet (5) has a lower strength than a conventional piercing rivet, but nevertheless a significantly higher ductility, in particular in the initial state without cold hardening, the strength of the piercing rivet (5) being between 600MPa and 1000MPa, in particular between 750MPa and 900 MPa.

9. A self-piercing rivet connection according to any one of the preceding claims, characterised in that the material thickness ratio between the first component (1) on the male mould side and the second component (3) on the female mould side is between 1:1 and 1:3, in particular the material thickness of the first component (1) on the male mould side is less than or equal to 1.3 mm.

10. A punch rivet for a self-piercing riveted connection according to any one of the preceding claims.

Technical Field

The invention relates to a self-piercing rivet connection according to the preamble of claim 1 and to a piercing rivet for a self-piercing rivet connection according to claim 10. The invention is used for connecting components made of deformable metal materials with low strength of up to 300MPa, in particular for joining aluminium materials.

Background

The self-piercing riveted connection according to the invention is preferably used in vehicle construction. In this case, the self-piercing rivet connection is designed in particular for dynamic and/or crash loads occurring in vehicles. In vehicle construction, the manufacture of vehicle bodies takes place in a fully automatic process chain in which, for example, aluminum semi-finished products (plates and cast material and profiles) are provided, joined by means of self-piercing rivet connections and subsequently painted in, for example, a KTL process.

In the self-piercing rivet connection according to the invention, at least two components made of a deformable metal material having a strength of up to 300MPa are connected to one another in a riveting process. During the riveting process, the punch rivet is driven with a set force (Setzkraft) through the first component on the male mold side and into the second component on the female mold side. In order to produce the undercut, the above-described procedure is carried out with a residual bottom thickness remaining in the second component on the die side and with the expanded diameter to which the punch rivet is expanded in the second component. The punch rivet can be made of wire, for example cold-forged steel, and has a corrosion-resistant layer added to the surface.

Such conventional punch rivets have an inner bore with a relatively large bore depth. The punch rivet can be produced, for example, in a total of five stages, two stages being required for producing the inner bore. Furthermore, in conventional punch rivets (due to the internal suction geometry thereof by the deep inner bore), the problem with the dipping method or with other coating methods is that the coating material flows into the inner bore of the punch rivet and closes the inner bore.

A punch rivet for connecting high-strength steels is known from DE 102013020504 a1, which has an arcuate recess at the shank end of the punch rivet. A punch rivet for joining two aluminum plates is known from EP 0833063A. A punch rivet for connecting two workpieces, in particular made of high-strength steel, is known from DE202016102528U 1.

Disclosure of Invention

The object of the invention is to provide a self-piercing rivet connection and a piercing rivet which can be produced more easily than in the prior art and which can be used for a greater number of material thickness combinations of the components to be joined.

This object is achieved by the features of claim 1 or 10. Preferred developments of the invention are disclosed in the dependent claims.

According to the characterizing part of claim 1, the punch rivet is designed such that, after the riveting process, it can be upset to 60% of its initial length in the undeformed state and at the same time the opening diameter can be increased to 140 to 150% of the shank diameter, but in particular only to 135 to 140% of the shank diameter, without damage to the punch rivet by tearing of the punch rivet material.

In one embodiment, the undeformed punch rivet can have a cylindrical shank with a flat recess which opens toward the shank tip and a rivet head with a larger diameter than the shank diameter. The recess is machined into the shank tip only to a lesser depth than in conventional punch rivets (which are simple in terms of machining technology). Due to the small recess depth (unlike the prior art), there is no internal absorption punch rivet geometry. Therefore, problems that occur in the leaching method or in other coating methods do not occur. The recess can be of truncated spherical, conical or frustoconical design.

Preferably, the base material of the punch rivet may have a significantly lower hardness (or strength) than conventional punch rivets, yet have a significantly higher ductility. In the initial state without cold hardening, the hardness of the punch rivet is preferably between 200HV1 and 320HV1, in particular between 250HV1 and 300HV 1. This corresponds almost to a strength of between 600MPa and 1000MPa, in particular between 750MPa and 900 MPa.

The core of the invention lies in the fact that the relatively low strength of the punch rivet, in combination with the later described punch rivet geometry, results in a special upsetting behavior of the punch rivet during the punching-in process. By means of the riveting and the die geometry, in particular, significantly different material thicknesses can be joined on the die side. The punch rivet according to the invention is more limited in terms of material thickness of the male-side counterpart than the known punch rivet elements due to the low hardness and the small inner bore depth. Preferably, the material thickness ratio between the member on the male mold side and the member on the female mold side may be any value between 1:1 and 1: 3.

The starting point of the invention is therefore a punch rivet which can be produced considerably more simply than a conventional semi-hollow punch rivet and which has only a flat recess at the shank tip instead of a deep bore. A punch rivet having a flattened internal recess on its shank tip is further improved in the above-described protruding upsetting capability. For this upsetting capability, in particular for the punch rivet material, the punch rivet head shape (for the setting force introduction) and the punch rivet foot geometry (for the setting force derivation) are very important: the head shape may be countersunk with a flat upper side of the rivet head. The rivet head upper side can transition radially outward on the head upper side into a circumferential head edge, which extends axially at a head-side height to the head lower side. The underside of the rivet head is connected to the underside of the head, and the underside of the rivet head transitions into the rivet shank with the diameter decreasing toward the shank tip. The shank tip has an annularly circumferential punching edge which delimits an internal recess, the wall of which intersects the shank circumference at the punching edge. Preferably, the upsetting capability according to the invention is facilitated by the soft punch rivet material compared to the prior art. Particularly preferred dimensions that are also important for the upsetting capability are set forth in the inventive aspects listed below in detail.

In the undeformed rivet state, the recess therefore preferably projects axially into the rivet shank starting from the shank tip with a recess depth. The recess depth can be between 10% and 25% of the total length of the punch rivet, in particular 15% of the total length of the punch rivet. In this way, a rivet head material thickness (referred to as the material thickness of the punch rivet along the longitudinal axis of the punch rivet) of between 75% and 90% of the total length of the punch rivet, in particular 85% of the total length of the punch rivet, is obtained. The rivet head material thickness is measured along the longitudinal rivet axis between the upper side of the rivet head and the spherical-truncated inner recess. Thus, the above rivet head may provide a sufficiently large amount of material for the material flow during the riveting process.

In terms of a sufficiently high connection strength of the self-piercing rivet connection, it is advantageous if, after the completion of the piercing process (i.e. the riveting process), the piercing rivet recess is substantially completely filled with the piercing rivet material due to the material flow. Preferably, therefore, the rod tip has a substantially flat end face after the riveting process.

During the punching-in process, material stresses are greatest, in particular at the transition between the rivet shank and the rivet head. In order to avoid tearing of the material at the rivet head/rivet shank transition, the transition can preferably be realized as follows: the transition can have a rivet head underside of rounded configuration, which has a constant head radius. The rounded rivet head underside may merge radially outward into a gentle, conical rivet head underside, which extends to the rivet head edge. The gentle, conical rivet head underside can be inclined upward in the direction of the rivet head upper side with respect to the angle of inclination of the transverse plane. Preferably, the above head radius is between 0.8mm and 2.0 mm. The angle of inclination/taper may be in the order of 20 °. Between the rivet head underside and the rivet head upper side, the radially outer rivet head edge extends over a head side height of, in particular, approximately 0.3 mm.

In order to further contribute to good upsetting behavior, it is preferred that the punch rivet is not realized as a round head rivet with a mushroom-shaped rivet head, but as a countersunk rivet (or flat head rivet) with a planar upper side of the rivet head. In the case of a self-piercing rivet connection, the rivet head top of the flat-head rivet is flush with the surface of the first component on the die side, i.e. is oriented without the head being raised, i.e. does not protrude over the entire component surface.

The cutting edge geometry formed on the rivet foot, that is to say on the shank tip, can have an annular, punch-in edge which circumferentially delimits the recess. During the punching-in process, the punching-in edge is pressed as a cutting edge, on the one hand, the punching rivet is prevented from upsetting in advance by the cutting edge, and on the other hand, the punching rivet is controlled to expand radially outwards by a predetermined expansion dimension. Preferably, the inner wall of the female punched rivet part and the shank circumference meet at the punched-in edge at an acute angle of, for example, 45 °. The punch-in edge may be rounded at a fillet radius in the range of 0.15 mm.

In the undeformed rivet state, the overall length of the punch rivet is in the range from 4mm to 8mm, in particular between 4.5mm and 6.0 mm. The rivet head diameter can be in the range from 4.5mm to 8.5mm, in particular 5.5mm or 7.75mm, while the rivet shank diameter is in the range from 2.8mm to 6.6 mm. Such rivet stem diameters can be handled using known riveters.

With the punch rivet according to the invention, the material thickness ratio between the first component on the male die side and the second component on the female die side can be between 1:1 and 1: 3. Here, the material thickness of the first member on the male die side is preferably less than or equal to 1.3 mm.

Drawings

Embodiments of the present invention are described next based on the drawings.

Wherein:

fig. 1 shows a micrograph of a punch rivet in the undeformed state;

fig. 2 shows a punch rivet in a punch rivet tool before the punching process is carried out in a rough schematic illustration; and

fig. 3 shows a self-piercing rivet connection.

Detailed Description

Fig. 3 shows a completed self-piercing rivet connection in which the aluminum plate 1 on the punch side and the aluminum plate 3 on the die side are connected to one another by means of a piercing rivet 5. In fig. 2 or 3, the two aluminum plate elements 1 have almost the same material thickness s₁、s₂. The punch rivet 5 has a rivet head 7 and a rivet shank 9. In the figures, the punch rivet 5 is realized as a flat head rivet with a planar, plane-parallel upper side 17 of the rivet head. In fig. 3, the rivet head top 17 is oriented flush with respect to the surface of the component 1.

In preparation for the punching-in process, the two components 1, 3 are placed one on top of the other on the matrix 11 of the riveting tool and are pressed together with a clamping force by means of a clamping system, not shown. Subsequently, the punch rivet 5 is driven into the two components 1, 3 with the aid of the punch 13 with the setting force F. During the punching process, the punch rivet 5 penetrates through the material of the die-side component 1 and is driven into the second component 3, specifically while retaining the residual bottom thickness r (fig. 3) of the die-side component 3 and while the punch rivet 5 expands to an expanded diameter d in the second component 3_ATo produce an inverted recess.

Next, the punch rivet 5 is described separately with reference to fig. 1: the rotationally symmetrical punch rivet 5 therefore has a truncated-spherical recess 15 which is open toward the shank tip and projects axially into the rivet shank 9 with a recess depth t. In fig. 1, the recess depth t is 15% of the total length l of the punch rivet. Conversely, the rivet head material thickness m, which extends along the rivet longitudinal axis L between the rivet head upper side 17 and the recess 15_KIs 85 percent of the total length l of the punch rivet. In fig. 1, the head is designed with a constant head radius d by rounding_KThe transition between the rivet shank 9 and the rivet head 7 is formed by the rivet head underside 16, the head radius being, for example, 1 mm. The rounded rivet head underside 16 merges tangentially radially outward into a flat, conical rivet head underside which extends to the rivet head edge 19. In fig. 1, the gentle, conical rivet head underside is inclined upward in the direction of the rivet head upper side at an inclination angle α (fig. 1) of approximately 20 ° relative to the transverse plane. Radially outwardly encircling rivet head edge 19At a head side height l of about 0.3mm_KExtending between a rivet head underside 16 and a rivet head upper side 17.

At the shank end facing away from the rivet head 7, a punch-in edge 21 is formed which surrounds in an annular manner and delimits the recess 15. The inner wall 23 of the punched rivet recess 15 and the shank circumference meet at an acute edge angle β on the punched-in edge 21, specifically at an edge angle β of approximately 45 °. In FIG. 1, with a fillet radius r of 0.15mm_aThe punch-in edge 21 is rounded.

In fig. 1, the overall length l of the punch rivet 5 in the undeformed state is 5mm, and the rivet head diameter d_KIs 5.5mm and the shank diameter d_SIs 2.9 mm. The base material of the punch rivet 5 is cold forged steel. In an initial state without cold hardening, the strength of the cold-forged steel is 750MPa to 900 MPa.

In combination with the above-described punch rivet geometry, the relatively low strength of the punch rivet 5 results in a special punch rivet upsetting behavior, in which, without tearing of the material in the punch rivet 5, the punch rivet 5 is upset to 60% of its initial length l (fig. 2) after the punching-in process and the expansion diameter d is increased_AIncrease to rivet shank diameter d_S135% to 150%. As can also be taken from fig. 3, after the punching-in process, the punched-in rivet recess 15 is filled substantially completely with the punched-in rivet material due to the material flow. Thus, in fig. 3, the stem tip of the punch rivet 15 is a substantially flat end face.

List of reference numerals

1 component on the male die side

3 parts on the die side

5 punching rivet

7 rivet head

9 rivet rod

11 concave die

13 male die

15 concave part

16 rivet head underside

17 rivet head upside

19 rivet head edge

21 punching edge

23 inner wall

d_SRivet shank diameter

d_KBetween rivet heads

d_ADiameter of opening

r_KRadius of head

Angle of inclination alpha

Angle of beta punching edge

r_ARounded angle of the punched-in edge

Total length of punched rivet

l_KHeight of head side

m_KThickness of rivet head material

t concave depth of concave portion

r residual bottom thickness

Longitudinal axis of L-shaped punch rivet

s₁、s₂Thickness of material

F set force