DE102012001651A1 - Device for mechanical joining of stacked plate-shaped joining partners, has shaping contour formed on surface on die, rivet penetrating rectilinearly into joint partners, and die comprising pressure contour at die surface - Google Patents

Abstract

The device (1) has joint partners (3, 5) on a die (9) arranged one above another by punch riveting with a rivet (7). A shaping contour (12) is formed on a die surface (10.1) on another die (10) below the joint partners. The rivet penetrates rectilinearly into the adding partners. The latter die comprises a pressure contour (14) at the die surface. The shaping contour is designed as recess (12.1) between an upper plane (12.4) formed by a die top face, and a lower plane (12.2). The pressure contour comprises rounded off or round cross section (14.2).

Description

The invention relates to a device for mechanical joining according to the preamble of patent claim 1.

Generic devices for the mechanical joining of superimposed joining partners by means of punch rivets are well known in the art. Such a device usually consists of a tool-side punch, which acts on a rivet head and a punch arranged opposite the die, which acts as a counter punch. During the joining process, the rivet is driven into the two joining partners, wherein the rivet shank of the rivet penetrates the first joining partner arranged above, in order to spread and connect to the material in the matrix-side joining partner in a material-displacing manner. Due to the tensile stresses occurring during the joining process, brittle light metal materials, such as, for example, aluminum alloys, magnesium casting alloys or 7000 aluminum alloys, tend to form cracks in the region of an upper side of the die-side joining partner with negative effects on the bonding quality. Preferably, the cracks form in the region of a forming contour of the upper side of the die-side joining partner, since particularly high tensile stresses occur during the joining process at this point. However, current measures to avoid cracks lead to restrictions of possible material combinations.

In the published patent application DE 199 40 803 A1 For example, a device for mechanical joining of superimposed joining partners is described by means of punch rivets. In punch riveting with a rivet or a so-called half-tubular rivet, the joining partners are connected to one another by using a punch provided above the joining partner and a die provided below the joining partner with a forming contour formed on the die surface, wherein the rivet penetrates substantially rectilinearly into the joining partners. In this joining process, with the forming contour of the die surface, the risk of crack formation in the die-side joining partner can indeed be reduced, but not completely eliminated.

The object of the invention is to provide a device for mechanical joining of superimposed joining partners, which allows a simple and cost-effective construction, a crack-free deformation in the region of the connection of the two joining partners.

According to the invention the object is achieved by a device for mechanical joining of superimposed joining partners with the features of claim 1. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

In order to provide a device for mechanical joining of superimposed joining partners, which allows a simple and cost-effective construction a crack-free deformation in the region of the connection of the two joining partners, the invention proposes that the die on the Matrizenoberfläche additionally has at least one pressure contour.

A significant advantage of the invention is that multi-axial compressive stress states can be induced in the die-side joining partner by a targeted arrangement of the pressure contour of the invention in the Matrizenoberfläche so that reduce existing tensile states during the joining process and the material of the die-side joining partner in semi-hollow riveting a greater plastic deformation capacity can achieve without cracking. In this context, "deformability" is to be understood as meaning in particular a property of a metallic material which can endure plastic deformation without material separation or cracking. Since the material's ability to change its shape depends, inter alia, on the particular state of stress, it is possible for the material, with a suitable influence on the stress state, to tolerate even greater changes in shape without cracking or even complete failure of the material. Advantageously, larger changes in shape than under tensile stresses are possible under compressive stresses, whereby the induced multiaxial compressive stress in the matrizenseitigen joining partners, even with brittle light metal materials ensures a crack-free deformation in the region of the connection of the two joining partners. Preferably, the pressure contour according to the invention in the die surface allows a reproducible high quality of connection of the two joining partners, without restrictions of possible material combinations. The more accurate and secure a ductile workpiece damage or a crack formation during the joining process can be excluded, the more the cost-effectiveness of the punch riveting process increases.

In an advantageous embodiment of the device according to the invention the forming contour is formed as a recess between an upper level formed by a Matrizenoberseite and a lower level. Preferably, the recess between the lower level and a feed area of the die forming Transition region on a first radius and between the transition region and the upper level on a tangentially expiring second radius. This means that parts of the forming contour of the die-side joining partner are designed as a spherical section with a constant curvature and a fixed radius. Such forming contours are almost insensitive to external influences and allow by the structurally simple geometry advantageously an accurate production of the forming contour with a high dimensional stability and torsional rigidity. Due to the tangential expiring first radius can be achieved in an advantageous manner in a simple manner an improvement of the optical design of the rivet joints produced by punch riveting. In an advantageous manner, the surface of the matrizenseitigen joining partner after the joining process of the two joining partners on a reproducible quality with flowing transitions, and therefore can also be applied in the outer skin of the vehicle body. Optically unfavorable contours with possibly mechanically disadvantageous effect can be avoided by tangential radii in the transition area.

In a further advantageous embodiment of the device according to the invention, the at least one pressure contour can be formed on the die surface of the die outside the transition region formed as a draw-in region of the die. Advantageously, the formability of the material and thus of the die-side joining partner can be specifically influenced by the skillful arrangement of the printing contour. Thus, by a previously introduced deformation of the die-side joining partner, a multiaxial compressive stress state outside the transition area formed as the draw-in area of the die is induced in the die-side joining partner, and the shape-changing ability or the deformations of the die-side joining partner are influenced and optimized outside the transition area formed as the draw-in area of the die. Preferably, the at least one pressure contour is formed on the die surface in the upper level of the reshaping contour of the die designed as a recess. In this way, the pressure contour is advantageously arranged in the area of the die surface with the greatest possible deformability. Such a pressure contour arranged in the region of the largest deformation advantageously induces a multiaxial compressive stress state, which in a simple manner can reduce the tensile stresses present during the joining process and thus form the region free of cracks. If necessary and according to the particular application, the at least one pressure contour can additionally or alternatively be formed on the die surface in the lower level of the forming contour of the die, which is designed as a recess.

In an alternative embodiment of the device according to the invention, the at least one pressure contour can be formed on the die surface within the transition region formed as a draw-in region of the die. As a result, in a defined region within the feed region of the die, the greatest formability or the greatest deformations of the die-side joining partner can be achieved.

In a further advantageous embodiment of the device according to the invention, the at least one pressure contour can be designed as a radially encircling or annular survey. Alternatively, the at least one pressure contour can be formed as a plurality of knob-shaped elevations. In both embodiments, the at least one pressure contour can advantageously have a rounded or round cross-section. This geometric design of the printing contour generated in an advantageous manner during the joining process on the matrizenseitigen side of the joining partner inevitably a negative image of the printing contour with radially encircling depressions or holes without sharp edges. The circular elevation with the radially encircling design of the printing contour simplifies the production of the die, whereby cost-intensive production time can be saved or high numbers or matrices with different properties with respect to deformability can be produced economically. Preferably, a circular annular radial circumferential survey as part of a matrix exceptionally well absorb high pressure forces during the joining process and is therefore particularly well suited for punch riveting with high quantities.

In an advantageous embodiment of the device according to the invention, at least two printing contours designed as radially circumferential elevations are formed with a predetermined lateral distance from one another on the die surface of the die. Depending on the desired degree of deformation and on the material used or on the combination of materials, the ability to modify the shape can be set particularly easily by means of the number and the spacing of the radially encircling elevations.

In a further advantageous embodiment of the device according to the invention, the survey starting from the die surface may have a height in the range of 01 to 0.8 mm. Since a material solidifies at excessive cold forming and thus reduces the deformability, the pressure contour according to the invention in an advantageous manner Only a small amount on. This is fundamentally adapted to the thickness of the material and to the desired deformation of the die-side joining partner, since a material which has been work-hardened by pre-forming with progressive deformation tends to crack.

Advantageous embodiments of the invention are illustrated in the drawings and will be described below.

Showing:

1 1 is a schematic sectional view of the parts according to the invention of a first exemplary embodiment of a device for punch riveting with a first exemplary embodiment of a die with a first exemplary embodiment of the pressure contour according to the invention;

2 a schematic sectional view of a second embodiment of the die for the device for punch riveting out 1 with a second embodiment of the printing contour according to the invention,

3 a schematic sectional view of a third embodiment of the die for the device for punch riveting 1 with a third embodiment of the printing contour according to the invention,

4 a diagram showing a shear strength as a function of a stress state,

5 a schematic sectional view joint connection without cracking, which with the second embodiment of the die 2 was manufactured, and

6 a schematic sectional view of a joint with cracking, which was prepared with a conventional joining device.

1 shows a device 1 for mechanical joining of superimposed joining partners 3 . 5 using punch rivets with a rivet 7 , Using one above the joining partner 3 . 5 provided stamp 9 and one below the joining partner 3 . 5 provided template 10 which one on the die surface 10.1 trained forming contour 12 shows, the rivet penetrates 7 essentially straight in the joining partners 3 . 5 one. Preferably, the superimposed joining partners 3 . 5 plate-shaped and may have different thicknesses. As materials brittle light metal materials, such as aluminum, aluminum alloys, magnesium casting alloys or 7000er aluminum alloys are used, although other materials are conceivable. Alternatively, the joining partners 3 . 5 consist of different materials, so that the device of the invention allows a wide variety of material combinations with different properties.

The rivet 7 is preferably designed as Halbhohlniet and is particularly ideal for the applications in the punch riveting or semi-hollow punch riveting, since it takes up loads during the joining process well and upsetting the Halbhohlnietfußes 7.1 can be reduced. After the joining process with the semi-tubular rivet 7 have the two joining partners 3 . 5 one in 5 illustrated positive rivet connection with a particularly high strength. Such semi-tubular rivets 7 are usually made of tempered steel, although other materials are conceivable.

To a device 1 for mechanical joining of superimposed plate-shaped joining partners 3 . 5 to create which with a simple and inexpensive construction a crack-free deformation in the region of the connection of the two joining partners 3 . 5 allows, is proposed according to the invention, that the die 10 at the die surface 10.1 additionally at least one pressure contour 14 having.

As a result, in semi-hollow punch riveting advantageously an application extension of the compound spectrum of brittle light metal materials, such as the hard-to-work materials die-cast aluminum or 7000er aluminum alloys.

4 Mohr's circle of stress graphically depicts the shear strength as a function of the stress state. A Mohr stress circle describes the stress state in a point of a body, with each point of intersection being assigned a point on the circle. As a result, the voltages for each cut and also the main stresses and the main shear stress can be read directly. In the present exemplary embodiment of the device according to the invention, during the joining process, an induction of multiaxial compressive stress states into the material of the die-side joining partner can be achieved 5 take place and thus the formability of a range of the combined tensile state to be shifted in a range of the combined compressive stress state, whereby the plastic deformation capacity of the material of the die-side joining partner 5 can be increased in an advantageous manner. Thus, the material of the matrizenseitigen joining partner 5 during the joining process in be advantageously exposed to a high tensile stress before it can cause cracking.

1 to 3 show three different embodiments of the die 10 . 10 ' . 10 '' for the mechanical joining device 1 ,

How out 1 to 3 it can be seen that is the forming contour 12 . 12 ' . 12 '' in the illustrated embodiments, each as a recess 12.1 between a top plane formed by a die top 12.4 and a lower level 12.2 formed, which the bottom of the recess 12.1 represents. The recess 12.1 points between the lower level 12.2 and a catchment area of the die 10 . 10 ' . 10 '' forming transitional area 12.3 a first radius 16.1 and between the transition area 12.3 and the upper level 12.4 a tangentially expiring second radius 16.2 on. In addition, the at least one pressure contour 14 . 14 ' . 14 '' in the illustrated embodiments in each case outside of the catchment area of the die 10 . 10 ' . 10 '' trained transition area 12.3 at the die surface 10.1 . 10.1 ' . 10.1 '' in the upper level 12.4 the matrix 10 . 10 ' . 10 '' educated. Additionally or alternatively, the at least one pressure contour 14 . 14 ' . 14 '' in embodiments not shown but also within as the catchment area of the die 10 . 10 ' . 10 '' trained transition area 12.3 at the die surface 10.1 . 10.1 ' . 10.1 '' and / or outside of as the catchment area of the die 10 . 10 ' . 10 '' trained transition area 12.3 at the die surface 10.1 . 10.1 ' . 10.1 '' in the lower level 12.2 the matrix 10 . 10 ' . 10 '' be formed. However, other positions which appear appropriate to a person skilled in the art or any combination of different positions of the printing contours are also suitable here 14 . 14 ' . 14 '' conceivable. Basically, the position of the at least one pressure contour 14 . 14 ' . 14 '' Determined by the position of the largest deformation, which locally optimal adjustment of the deformability of the die-side joining partner 5 can be adjusted.

How out 1 it can be seen, is the pressure contour 14 in the illustrated first embodiment as a radially encircling or circular survey 14.1 with a rounded cross-section 14.2 executed. The height h of the radially encircling or annular survey 14.1 lies starting from the matrix surface 10.1 preferably in the range of 0.1 to 0.8 mm.

How out 2 it can be seen comprises the pressure contour 14 ' in the illustrated second embodiment, two radially encircling or annular elevations 14.1 with a rounded cross-section 14.2 , The height h of the radially encircling or annular elevations 14.1 lies starting from the matrix surface 10.1 ' analogous to the first embodiment, preferably in the range of 0.1 to 0.8 mm. A lateral distance A between the two radially encircling or annular elevations 14.1 can be specified in the range of 0.5 to 5 mm, depending on the desired degree of deformation and on the material used or on the material combination, preferably in the range of 0.5 to 5 mm.

How out 3 it can be seen comprises the pressure contour 14 '' in the illustrated third embodiment, five radially encircling or annular elevations 14.1 with a rounded or round cross-section 14.2 , The height h of the radially encircling or annular elevations 14.1 lies starting from the matrix surface 10.1 '' analogous to the first and second embodiments, preferably in the range of 0.1 to 0.8 mm. The number of radially encircling or annular elevations 14.1 and the lateral distance A between each two radially encircling or annular elevations 14.1 can be selected depending on the desired degree of deformation and the material used or on the material combination. In this case, between each two radially encircling or annular elevations 14.1 the same or different distances A are preferably specified in the range of 0.5 to 5 mm.

In an alternative embodiment, not shown, of the present invention, the at least one pressure contour may comprise a plurality of knob-shaped elevations, each having a rounded or round cross-section.

The mode of action of the pressure contour according to the invention 14 . 14 ' . 14 '' is from the in 5 shown rivet connection with the die 10 ' according to 2 was produced. How out 5 can be seen, have on the matrizenabgewandten side of the joining partner 5 in one area 5.1 with increased tension during the joining process no cracks 18 formed because the pressure contour 14 ' in the Matriceside joining partner 5 induced a multiaxial compressive stress state, whereby existing tensile states during the joining process can be reduced and the material of the die-side joining partner 5 can achieve a greater plastic deformation capacity in semi-hollow punching rivets.

In contrast to 5 shows 6 a rivet joint with cracking, which with a conventional device without the pressure contour according to the invention 14 . 14 ' . 14 '' was produced. How out 6 it can be seen that points there used die 100 one on the die surface 110 trained forming contour 112 without pressure contour according to the invention 14 . 14 ' . 14 '' on. Due to the high tensile stresses form on the matrizenabgewandten side of the joining partner 5 in the area 5.1 with increased tensile stress during the joining process cracks 18 out.

LIST OF REFERENCE NUMBERS

1

joining device

3, 5

joining partner

5.1

Area with increased tension

7

rivet

7.1

Halbhohlnietfuß

9

stamp

10, 10 ', 10' '

die

10.1, 10.1 ', 10.1' '

die surface

12, 12 ', 12' '

Umformkontur

12.1

recess

12.2

lower level (matrix surface)

12.3

Transition area

12.4

upper level (matrix surface)

14, 14 ', 14' '

pressure contour

14.1

radially encircling elevation (circular ring)

14.2

cross-section

16.1

first radius

16.2

second radius

18

Crack

H

height

A

distance

100

conventional die

110

die surface

112

Umformkontur

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19940803 A1 [0003]

Claims (10)

Device for mechanically joining superimposed joining partners ( 3 . 5 ) by means of punch rivets with a rivet ( 7 ), using one above the joining partner ( 3 . 5 ) provided stamp ( 9 ) and one below the joining partner ( 3 . 5 ) template ( 10 . 10 ' . 10 '' ) with one on the die surface, ( 10.1 . 10.1 ' . 10.1 '' ) formed forming contour ( 12 . 12 ' . 12 '' ), wherein the rivet ( 7 ) substantially rectilinearly into the joining partners ( 3 . 5 ) penetrates, characterized in that the die ( 10 . 10 ' . 10 '' ) on the die surface ( 10.1 . 10.1 ' . 10.1 '' ) additionally at least one pressure contour ( 14 . 14 ' . 14 '' ) having. Apparatus according to claim 1, characterized in that the forming contour ( 12 . 12 ' . 12 '' ) as a recess ( 12.1 ) between an upper level formed by a die top ( 12.4 ) and a lower level ( 12.2 ) is trained. Device according to claim 2, characterized in that the recess ( 12.1 ) between the lower level ( 12.2 ) and a catchment area of the die ( 10 . 10 ' . 10 '' ) transitional area ( 12.3 ) a first radius ( 16.1 ) and between the transitional area ( 12.3 ) and the upper level ( 12.4 ) a tangentially expiring second radius ( 16.2 ) having. Apparatus according to claim 2 or 3, characterized in that the at least one pressure contour ( 14 . 14 ' . 14 '' ) outside of the feed area of the die ( 10 . 10 ' . 10 '' ) transitional area ( 12.3 ) on the die surface ( 10.1 . 10.1 ' . 10.1 '' ) is trained. Apparatus according to claim 4, characterized in that the at least one pressure contour ( 14 . 14 ' . 14 '' ) on the die surface ( 10.1 . 10.1 ' . 10.1 '' ) in the upper level ( 12.4 ) and / or in the lower level ( 12.2 ) as a recess ( 12.1 ) formed forming contour ( 12 . 12 ' . 12 '' ) is trained. Apparatus according to claim 2 or 3, characterized in that the at least one pressure contour ( 14 . 14 ' . 14 '' ) within the catchment area of the die ( 10 . 10 ' . 10 '' ) transitional area ( 12.3 ) on the die surface ( 10.1 . 10.1 ' . 10.1 '' ) is trained. Device according to one of claims 1 to 6, characterized in that the at least one pressure contour ( 14 . 14 ' . 14 '' ) as a radial circumferential survey ( 14.1 ) or is designed as a plurality of knob-shaped elevations. Device according to one of claims 1 to 7, characterized in that the at least one pressure contour ( 14 . 14 ' . 14 '' ) has a rounded or round cross-section ( 14.2 ) having. Apparatus according to claim 7 or 8, characterized in that at least two as radially encircling elevations ( 14.1 ) executed printing contours ( 14 ' . 14 '' ) with a predetermined lateral distance (A) to each other on the die surface ( 10.1 . 10.1 ' . 10.1 '' ) are formed. Device according to one of claims 1 to 9, characterized in that the survey ( 14.1 ) starting from the die surface ( 10.1 . 10.1 ' . 10.1 '' ) has a height (h) in the range of 0.1 to 0.8 mm.

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