EP1576295A1

EP1576295A1 - Stamped rivet for connection to sheet metals and method for placing said stamped rivet

Info

Publication number: EP1576295A1
Application number: EP03785833A
Authority: EP
Inventors: Erich Palm
Original assignee: SFS Intec Holding AG
Current assignee: SFS Group International AG
Priority date: 2002-12-18
Filing date: 2003-12-16
Publication date: 2005-09-21
Also published as: US20060039777A1; WO2004055397A1; AU2003294863A1; DE10259334C1

Abstract

The stamped rivet (10) has a head (12), a shank (14), a peripheral groove (16) formed therein and a shank end (18). The head (12) is provided with a ring-shaped planar surface (20). The peripheral groove (16) is directly adjacent to the lower side of the head (12). One section (22) of the shank is conically tapered in an area located between the peripheral groove (16) and the end (18) of the shank in the direction of the end (18) of said shank. The axial length (L) of the peripheral groove (16) is greater than the thickness of the sheet metal or the overall thickness of the sheet metals upon which a connection to the stamped rivet (10) is to be produced. The Peripheral groove (16) extends to a longitudinal centre (M) of the stamped rivet (10). The length of the tapered section (22) of the shaft (14) corresponds to the axial length (L) of the peripheral groove (16). Sheet metal material, which is forced downwards and to the side during formation of a stamped hole, is plastically deformed into the peripheral groove (16) during the stamping-in process. The axial thickness of the sheet metal material is greater in said deformation area than that of the starting material.

Description

Applicant: SFS intec Holding AG, CH-9435 Heerbrugg (Switzerland)

Subject: punch rivet for a connection to metal sheets and method for setting such a punch rivet

description

The invention relates to a punch rivet for a connection to metal sheets, with a head, with an adjoining shaft, with a circumferential groove formed in the shaft and with a shaft end opposite the head.

The invention further relates to a method for setting a punch rivet according to one of claims 1 to 17, for a connection to sheets, the punch rivet being pressed through the sheet without pre-drilling to form a punch hole and then pressed by means of counterpressure sheet metal material with plastic deformation into the circumferential groove ,

A punch rivet of the aforementioned type is known from EP 1 013 945 B1. This well-known rivet is not only a punch rivet, but also an embossed rivet. If such a punch-embossed rivet has punched through two components to be connected with one another to form a punch hole, a groove is then embossed around the shaft end facing away from the rivet head in the component there, whereby material of the component there is plastically deformed into the circumferential groove formed in the shaft penetrates. For this purpose, a die of the rivet setting device must be provided with an upwardly projecting ring collar which receives the shaft end opposite to the head and thereby stamps the groove around the shaft end into the material of the component there. The circumferential groove in this known shank embossed rivet is directly adjacent to the shank end, so that the plastic deformation takes place only in the material of the lower component. The head of the punch-embossed rivet is frustoconical and is pressed into the upper component when the rivet is placed so that the top of the head of the set rivet is flush with the top of the upper component. Such a stamped-embossed rivet requires a correspondingly complex rivet setting because of the required embossing process Contraption. In addition, sufficient material can only be deformed into the circumferential groove by the embossing if the components to be connected have a sufficient thickness. The known stamped-embossed rivet is obviously neither intended nor suitable for joining together thin sheets or for fastening in a thin sheet.

A similar punch-embossed rivet is known from US-A-3 909 913. The main difference between this punch and embossed rivet is that of a slightly different shape of the head and the circumferential groove. However, US-A-3 909 913 additionally shows the structure of the die which is used for the embossing process.

DE 297 07 669 U1 describes a punch rivet, which according to the above definition is also a punch-rivet. This document shows an old design of such a stamped embossed rivet, in which the circumferential groove is arranged closer to the point of separation of two components to be connected to one another than in the stamped embossed rivet according to EP 1 013 945 B1, so that material is not only produced by the embossing process lower component is plastically deformed into the circumferential groove, but also that the material of the upper component is deformed into the circumferential groove due to the frustoconical rivet head. However, even this known punch rivet is not suitable for joining thin sheets together, because they cannot provide enough material to be deformed for the two aforementioned shaping processes.

From US-A-4 130 922 a punch-embossed rivet is known, with which even thin components or sheets can be connected to one another, however, in order to set this rivet, both the die and a male must be designed as an embossing tool, and not only a groove can be embossed in the component there around the shaft end, but also a groove around the rivet head in the other component.

A corresponding prior art is also shown in US Pat. No. 5,678,970, in which both the female and the male are designed as embossing tools. If only the die is designed as an embossing tool, a rivet is used in which the head has a larger diameter than the shaft end. During the setting process, the head is countersunk flush in the upper component and a groove is only embossed around the end of the shaft in the lower component. From US-A-4 978 270 a headless punch-embossing rivet is known which not only requires a die designed as an embossing tool and a male formed as an embossing tool, but also has a plurality of circumferential grooves. It makes it possible to connect three components arranged one above the other.

Finally, DE 43 33 052 C2 shows a self-punching fastening device in which the rivet consists of a rivet head and a rivet shank with a central recess, the free end face of which does not completely punch through a sheet metal plate receiving it. Such a rivet is neither intended nor suitable for setting in thin sheet metal.

For a connection to sheet metal, not only punch rivets are known which connect two or more than two sheets to one another, but also punch rivets which are fastened to a sheet metal, the head of such punch rivets being able to be designed, for example, as a bearing journal (US-A- 3 571 903). The shank can be designed so that during the setting process sheet material surrounding the shank is displaced upward, which is then pressed down again by the bearing part of the punch rivet in order to be pressed into the circumferential groove by plastic deformation and thus the punch rivet in the sheet metal in a form-fitting manner set. Even such punch rivets cannot be placed in thin sheet metal. In this known punch rivet, there is also an embodiment in which a portion of the shaft tapers in a region between the circumferential groove and the shaft end in the direction of the shaft end, but in this embodiment the rivet is not a punch rivet, but requires one in it Sheet metal prefabricated conical opening in which it is secured by a special design of the shaft part located above the circumferential groove by sheet metal material which is plastically deformed into the circumferential groove.

For the setting of punch rivets of the aforementioned type, it is also known (US-A-1 275 576) to additionally use an embossing patrix and to additionally stake the head in the groove embossed by the embossing patrix.

The object of the invention is to design a punch rivet of the type mentioned at the outset in such a way that a secure connection can be established on thin sheets, be it for connecting a plurality of thin sheets together or for connecting the punch rivet to a thin sheet. The invention is also intended to provide a method for setting such a punch rivet. This object is achieved according to the invention in the case of a punch rivet of the type mentioned at the outset in that the head is provided with an annular flat surface on an underside facing the shaft, in that the circumferential groove adjoins the underside of the head directly and in that a section of the shaft is in one between the circumferential groove and the shaft end tapered towards the shaft end.

In the punch rivet according to the invention, the shaft has its thickest part in an area located between the circumferential groove and the shaft end, so that the plastic deformation of sheet metal material into the circumferential groove takes place immediately below the head and which extends from the thickest part of the shaft to that Shaft-end tapered section can be formed with a view to achieving an efficient punching effect. The shaft length of the punch rivet below the head is much greater than the thickness of the sheet or the total thickness of the sheet to which a connection is to be made. To establish such a connection, it is only necessary that, when a punching hole is formed, material displaced in the punching direction is pressed back during the setting process in such a way that it is plastically deformed into the circumferential groove.

Advantageous embodiments of the punch rivet according to the invention form the subject of the subclaims.

If, in an advantageous embodiment of the punch rivet according to the invention, the tapering section extends to a cylindrical end section of the shaft, the end section can be formed particularly efficiently for the punching process in terms of length and diameter.

If, in a further embodiment of the punch rivet according to the invention, the tapering section extends as far as the shaft end, the shaft end can, for example, be tapered so that less pressure is required for the punching process.

If, in a further embodiment of the punch rivet according to the invention, the tapered section directly adjoins the circumferential groove, a small overall length of the punch rivet can be achieved. If, in a further embodiment of the punch rivet according to the invention, a cylindrical shank section directly adjoins the circumferential groove and extends to the tapering section of the shank, regardless of whether a connection is made to one or more thin sheets, the protruding part after the setting process Insert the shaft part as a journal or the like.

If, in a further embodiment of the punch rivet according to the invention, the circumferential groove extends to a longitudinal center of the punch rivet, a sufficient axial length is also suitable for use with thin sheet metal material for plastically deforming the sheet metal material into the circumferential groove for secure, form-fitting holding of the punch rivet according to the invention available.

If, in a further embodiment of the punch rivet according to the invention, the tapering section of the shaft has an axial length which is substantially equal to the axial length of the circumferential groove, the region of the shaft located between the circumferential groove and the shaft end can be used for a particularly efficient punching process and / or design for use of the punch rivet as a bearing or the like.

If, in further refinements of the punch rivet according to the invention, the circumferential groove merges with a first radius into the flat surface on the underside of the head and / or the circumferential groove is parallel to the longitudinal axis in a region at the bottom that is central with respect to a longitudinal axis of the punch rivet and / or the circumferential groove merges with a straight line inclined against the longitudinal axis of the punch rivet into a subsequent shank section and / or the base of the circumferential groove merges into the straight line with a second radius and / or the circumferential groove with a third radius merges into a subsequent shank section and / or the tapered section with a fourth radius in the cylindrical end section and / or the cylindrical shaft section with a fifth radius in the tapered section, the connection of the punch rivet to the sheet can be tailored to the thickness and type of sheet metal material and to the end purpose of the punch rivet.

If, in a further embodiment of the punch rivet according to the invention, the shaft end is formed with sharp edges, the punching process can be tailored into the circumferential groove with a view to the desired plastic deformation of the sheet metal material. If, in a further embodiment of the punch rivet according to the invention, the cylindrical end section of the shaft has a diameter which is equal to the smallest or somewhat smaller than the smallest diameter of the shaft in the region of the circumferential groove, the amount of sheet metal material which is involved in the punching process can be reduced the punch hole is displaced outwards and in the punching direction and which is to be plastically deformed into the circumferential groove, optimally determine in advance.

If in a further embodiment of the punch rivet according to the invention an axial length of the circumferential groove is greater than the thickness of the sheet or the total thickness of the sheets to which a connection is to be made, the punch rivet according to the invention can also be used to secure a thin sheet Establish connection.

With regard to the method mentioned at the outset, the object is achieved according to the invention in that the sheet metal material is displaced in the punching direction in a first annular region surrounding the punch hole with the punch rivet, and then the sheet metal material is pushed upwards on the punch rivet by a counterforce exerted from below, that the punch rivet is then pressed further down through the punch hole until the head rests with its flat surface on the metal sheets, and that the sheet metal material displaced in the punching direction is plastically deformed into the circumferential groove by the counterforce.

Exemplary embodiments of the invention are described in more detail below with reference to the drawings. Show it

1a - 1c a first embodiment of a punch rivet according to the invention in

Side view, in top view or in perspective,

2a shows the punch rivet according to FIGS. 1a-1c for connecting two sheets together in the set state, a detail of a device for setting the punch rivet being additionally shown,

2b shows a second embodiment of the punch rivet according to the invention for connecting two sheets together, also in the set state, Fig. 3 shows a first embodiment of the device for setting the punch rivet according to the invention and

Fig. 4 shows a second embodiment of the device for setting

Punch rivets according to the invention, which is arranged here with further punch rivets in a magazine strip.

FIG. 1 a shows a top view of a first embodiment of a punch rivet according to the invention, which is designated overall by 10. A second embodiment of the punch rivet according to the invention is shown in FIG. 2b and is designated overall by 10 '. 2b is discussed further below.

As shown in FIGS. 1 a - 1 c, the punch rivet 10 has a head 12, an adjoining shank 14, a circumferential groove 16 formed in the shank and a shank end 18 opposite the head. The head 12 is on one of the shanks 14 facing underside with an annular flat surface 20. The circumferential groove 16 connects directly to the underside of the head 12. A section 22 of the shaft 14 tapers conically in a region located between the circumferential groove 16 and the shaft end 18 in the direction of the shaft end 18. In the exemplary embodiment shown, the head 12 is a flat head, as is shown in FIGS. 1a and 1b without further can be seen, but it could also be a semicircular head or the like. It is essential for the invention that the plane surface 20 adjoins the circumferential groove 16, the purpose of which will become clear below.

The punch rivet 10, 10 'described here is used for a connection on thin sheets, ie either for connecting two thin sheets 24, 26 to one another, as shown in FIGS. 2a and 2b, or for more than two thin sheets (not ) shown. The punch rivet 10, 10 'can also be attached to a thin sheet. In this case, the connection would look as in FIGS. 2a and 2b, only with the difference that the dividing line visible there between the two sheets 24, 26 would not be present. The single thin sheet could of course be thinner than the two thin sheets 24, 26 together. In any case, in the two embodiments shown in FIGS. 1 and 2, the punch rivet 10, 10 'according to the invention has an axial length L (FIG. 1a) or L' (FIG. 2b) of the circumferential groove 16 which is larger than the thickness of a single sheet to which the punch rivet 10 or 10 'is to be attached, or the total thickness of the sheets 24, 26 which are to be connected to one another by the punch rivet 10, 10'. at In the embodiment of the punch rivet 10 shown in FIG. 1, the tapered section 22 of the shank 14 extends to a cylindrical end section 28 which has an outer diameter D1. In the embodiment of the punch rivet 10 'shown in FIG. 2b, the tapered section 22' extends to a tip section 32 which tapers as the tapered section 22 'and ends in the shaft end 18' designed as a tip. The tapered section 22, 22 'can directly adjoin the circumferential groove 16, 16' (not shown). In the embodiments of the punch rivet 10, 10 'shown and described here, a cylindrical shaft section 30 or 30' directly adjoins the circumferential groove 16 or 16 'and extends as far as the tapering section 22 or 22' of the shaft 14.

In both embodiments of the punch rivet 10, 10 ', the circumferential groove 16, 16' extends to a longitudinal center M or M 'of the punch rivet. The tapered section 22, 22 'of the shaft 14, 14' has an axial length V or V which is substantially equal to the axial length L or L 'of the circumferential groove 16, 16'. In the first embodiment of the punch rivet 10, the tapered section with the length V is also followed by the cylindrical end section 28. In the case of the punch rivet 10 ′, the tip section 32 is also connected to the axial length V of the tapering section. The total length of the punch rivet 10, 10 'is thus substantially greater than and preferably more than twice as large as the total thickness of the sheet metal material on which the connection to or through the punch rivet 10, 10' is to be made.

In the case of the punch rivet 10, like the punch rivet 10 ', the circumferential groove 16 or 16' merges with the first radius R1 into the flat surface 20, 20 'on the underside of the head 12'. The circumferential groove 16, 16 'is parallel to the longitudinal axis 34, 34' in a region 36, 36 'at the bottom with respect to a longitudinal axis 34, 34' of the punch rivet 10, 10 '. In the punch rivet 10, the circumferential groove 16 merges with a straight line 38 inclined against the longitudinal axis 34 of the punch rivet into the subsequent cylindrical shank section 30, which is the thickest part of the shank 14, 14 'and has a diameter D2. The bottom of the circumferential groove 16 merges into a straight line 38 in the punch rivet 10 with a second radius R2. In the punch rivet 10 ', the circumferential groove 16' merges with a third radius R3 (FIG. 2b) into the subsequent cylindrical shank section 30 ', which likewise has the largest shank diameter D2. In the case of the punch rivet 10, the tapered section 22 merges into the cylindrical end section 28 with a fourth radius R4. Furthermore, in the case of the punch rivet 10, the cylindrical shank section 30 merges into the taper section 22 with a fifth radius R5. The diametrically opposite in FIG. Opposed two straight lines 38 enclose an angle α of 60 °. The shaft end 18 is formed with sharp edges in the punch rivet 10. Finally, in the case of the punch rivet 10, the diameter of the cylindrical end section 28 of the shaft 14 is equal to the smallest or somewhat smaller than the smallest diameter d of the shaft 14 in the region of the circumferential groove 16.

In both embodiments, the punch rivet 10, 10 'consists of a material that is harder than the sheet metal material to which a connection is to be made with the punch rivet. In both cases, the punch rivet 10, 10 'is not deformed during the setting process. Only the sheet metal on which a connection is to be made is deformed. When the connection is made, the sheet metal material is plastically deformed into the circumferential groove 16, 16 '. This results in a positive connection between the punch rivet 10, 10 'and the material of the sheets 24, 26, which is enclosed in the circumferential groove 16, 16' between the flat surface 20, 20 'and a shoulder, through the straight line 38 and through the radius R3 is formed.

FIG. 3 shows a first embodiment of a device, generally designated 40, for setting a punch rivet, here the punch rivet 10. The device 40 consists of a male part, generally designated PA, and a male part, generally designated MA, between which, in the illustration in FIG. 3, the two sheets 24, 26 to be connected to one another by the punch rivet 10 are clamped. The male part PA and the female part MA are connected to each other by a U-shaped yoke 42. In FIG. 4 it can be seen that the yoke 42 'can be attached to an electrically, hydraulically or compressed air operated tool 44' which drives a punch 46 'during the setting process. The drive of the stamp 46 is not shown in FIG. 3. The drive in FIG. 3 can be designed as in FIG. 4 or it can be done by hand, for example with a hammer.

In the device 40 according to FIG. 3, the male part PA has an upper sleeve 48 which receives the punch 46 and the punch rivet 10 in a displaceable manner and in turn is held fixedly or displaceably in the yoke 42. The die MA has a fixed lower bush 50, which is spaced from the upper bush 48 and receives the shaft 14 of the punch rivet 10 during the setting process. The lower bush 50 is surrounded by a resiliently preloaded clamping bush 52 which projects above the lower bush 50 in the direction of the punch 46 and serves as a support for the sheets 24, 26 which are to be connected to one another by the punch rivet 10. The punch 46 of the device 40 has a diameter which corresponds to the diameter of the head 12 of the punch rivet 10. The fixed lower sleeve 50 has an outer diameter which is larger than the diameter of the head 12 of the punch rivet 10. The lower sleeve 50 has an inner diameter D3. The inner diameter D3 is equal to the diameter D2 of the cylindrical shaft section 30 or slightly larger than the diameter D2. The outer diameter of the lower bush 50 is larger than the diameter of the head 12 of the punch rivet 10 by the difference between the diameter of the head 12 and the largest diameter D2 of the shaft 14 of the punch rivet 10, that is to say the diameter D2 of the cylindrical shaft section 30 2a additionally shown detail of the device 40 shows that the diameters specified above are dimensioned in order to create suitable space for the plastic deformation of the metal sheets 24, 26 in the region of the circumferential groove 16.

3 and 4, the clamping sleeve 52, 52 'has an annular shoulder 54, 54', which by a between an abutment 56, 56 ', to which the lower sleeve 50, 50' is attached, and the annular shoulder 54, 54 'arranged spring element 60, 60' is resiliently biased against a stop 62, 62 'which is formed by a shoulder of an inner threaded sleeve 64, 64' which is screwed into an outer threaded sleeve 66, 66 'of the die MA. In the exemplary embodiment shown, the spring element 60, 60 'is a package composed of a plurality of disc springs 68, 68' stacked one above the other.

The exemplary embodiment of the device 40 'according to FIG. 4 differs from the exemplary embodiment of the device 40 according to FIG. 3, except for the other type of drive, essentially in that at a stamp exit end 70 of the upper sleeve 48' there is a guide part, designated overall by 72 a punch rivet magazine strip 74 is attached.

The method for setting the punch rivet 10 with the device 40, in which the punch rivet is pushed through the sheets 24, 26 without pre-drilling to form a punch hole and then sheet material is pressed into the circumferential groove 16 with plastic deformation, is carried out as follows. First, the punch rivet 10 is pressed down with the aid of the punch 46 until it rests on the sheet 24. Subsequently, the plates 24, 26 are moved together with the clamping sleeve 52 against the force of the plate springs 68 by the punch 46 and the punch rivet 10 until the plate 26 rests on the upper side of the lower bush 50. From then on, the stamp 46 moves alone the punch rivet 10 and the hole is punched out through the cylindrical end section 28 of the punch rivet 10. When the punch hole is formed, the sheet metal material is carried along in a punching direction in a first annular region surrounding the punch hole. Edge areas of the punch hole are deformed downward. As soon as the sheets 24, 26 have been punched through, there is a relief through which the forces of the plate springs 68 become active again. These move the clamping sleeve 52 together with the sheets 24, 26 upwards again, to the extent that the forces of the plate springs 68 are able to move the sheets 24, 26 on the tapering section 22 of the rivet 10, which tapered upwards to slide up. The limit position would then be reached, provided that the force of the plate springs 68 is sufficient when the plate 24 rests on the underside of the upper bush 48. The sheets 24, 26 have now been lifted off the lower sleeve 50 again, so that there is a distance between the sheets 24, 26 and the top of the lower sleeve 50. In the meantime, the punch 46 has been continuously advanced. Due to the sudden release of the force of the plate springs 68, the sheets 24, 26 have been pushed up relatively far on the punch rivet 10 in the region of the punched hole. Due to the continued pressure exerted by the punch 46 on the punch rivet 10, this is finally pushed further down through the punch hole until the head 12 rests with its flat surface 20 on the top of the sheet 24. From now on, the punch rivet 10 and the sheets 24, 26 are moved downwards together until the sheet 26 rests on the upper side of the lower sleeve 50. Now the downwardly deformed edge regions of the punched hole are plastically deformed into the circumferential groove 16 in a first annular region B1 (FIG. 2a) with the aid of the stamp 46 on the lower bush 50 serving as a fixed abutment. The final state of this deformation is shown in Fig. 2a. During this deformation, a second annular region B2 surrounding the lower bush 50 is supported elastically and elastically by the clamping bush 52. The sheet metal material is compressed to the axial length L of the circumferential groove 16 in the deformation in the first annular region B1. The thin sheets 24, 26 to be connected to one another or the thin sheet to be connected to the punch rivet 10 preferably have an overall thickness that is less than the length L of the circumferential groove 16. However, the overall thickness could also be greater than the length L of the circumferential groove 16 By means of the setting method according to the invention, the sheet material in the preferred exemplary embodiment shown is thickened in the region of the circumferential groove 16 along its length L. The setting process takes place with the device 40 'according to FIG. 4 essentially as with the device 40 according to FIG. 3. FIG. 4 shows that the sheets 24, 26 are not clamped between the male part PA and the female part MA during the setting process need to be. Both in the device 40 according to FIG. 3 and in the device 40 'according to FIG. 4, the punch 46, 46' moves the punch rivet 10, 10 'downward during the setting process, this being the case when the sheets 24, 26 are punched through Collet 52, 52 'presses down against the force of spring element 60, 60' until sheet 26 rests on top of lower sleeve 50, 50 ', and when forming the punched hole, the sheet metal material in a first annular surrounding the punched hole Area is taken in the punching direction. At this moment, the counter pressure of the spring element 60, 60 'begins to exceed the force exerted from above, so that the clamping sleeve 52, 52' is suddenly pushed upwards by the spring element 60, 60 'in order to achieve this in the first annular region B1 To deform sheet metal upwards and into the circumferential groove 16, 16 '. The punching process and the deformation of the sheet material take place as described above.

Claims

Applicant: SFS intec Holding AG, CH-9435 Heerbrugg (Switzerland) Subject: punch rivet for a connection to metal sheets and method for setting such a punch rivet

1. punch rivet for a connection to sheet metal, with a head, with an adjoining shaft, with a circumferential groove formed in the shaft and with a shaft end opposite the head, characterized in that the head (12, 12 ') on a the underside facing the shaft (14, 14 ') is provided with an annular flat surface (20, 20') that the circumferential groove (16, 16 ') directly adjoins the underside of the head (12, 12') and that a Section of the shaft (14, 14 ') in a between the circumferential groove (16,

16 ') and the shaft end (18, 18') located towards the shaft end

(18, 18 ') tapered.

2. Punch rivet according to claim 1, characterized in that the tapering section (22) extends to a cylindrical end section (28) of the shaft (14).

3. punch rivet according to claim 1, characterized in that the tapering section (22 ') extends to the shaft end (18').

4. punch rivet according to one of claims 1 to 3, characterized in that the tapering section (22, 22 ') directly adjoins the circumferential groove (16, 16').

5. punch rivet according to one of claims 1 to 3, characterized in that a cylindrical shank section (30, 30 ') directly adjoins the circumferential groove (16, 16') and up to the tapering section (22, 22 ') of the shank ( 14, 14 ') is sufficient.

6. punch rivet according to one of claims 1 to 5, characterized in that the circumferential groove (16, 16 ') extends to a longitudinal center (M, M') of the punch rivet (10, 10 ').

7. punch rivet according to one of claims 1 to 6, characterized in that the tapering section (16, 16 ') of the shaft (14, 14') has an axial length (V, V) which is substantially equal to the axial length (L , L ') of the circumferential groove (16, 16').

8. punch rivet according to one of claims 1 to 7, characterized in that the circumferential groove (16, 16 ') with a first radius (R1) in the plane surface (20, 20') on the underside of the head 12, 12 ') ,

9. punch rivet according to one of claims 1 to 8, characterized in that the circumferential groove (16, 16 ') in a central region (36, 36.) In relation to a longitudinal axis (34, 34') of the punch rivet (10, 10 ') ') is parallel at the bottom to the longitudinal axis (34, 34').

10. punch rivet according to one of claims 1 to 9, characterized in that the circumferential groove (16) with a straight line (38) inclined against the longitudinal axis (34) of the punch rivet (10) merges into a subsequent shank section (30).

11. punch rivet according to claims 9 and 10, characterized in that the base of the circumferential groove (16) with a second radius (R2) merges into the straight line (38).

12. punch rivet according to one of claims 1 to 9, characterized in that the circumferential groove (16) with a third radius (R3) merges into a subsequent shaft portion (30 ').

13. punch rivet according to claim 2, characterized in that the tapered section (22) with a fourth radius (R4) merges into the cylindrical end section (28).

14. punch rivet according to claim 5, characterized in that the cylindrical shaft portion (30) with a fifth radius (R5) merges into the tapered portion (22).

15. punch rivet according to one of claims 1 to 14, characterized in that the shaft end (18) is formed with sharp edges.

16. punch rivet according to claim 2, characterized in that the cylindrical end portion (28) of the shaft (14) has a diameter (D1) which is equal to the smallest or slightly smaller than the smallest diameter (d) of the shaft (14) in the region the circumferential groove (16).

17. punch rivet according to one of claims 1 to 16, characterized in that an axial length (L, L ') of the circumferential groove (16, 16') is greater than the thickness of the sheet or the total thickness of the sheets (24, 26), to which a connection is to be made.

18. A method for setting a punch rivet according to any one of claims 1 to 17, for a connection to sheet metal, wherein the punch rivet is pressed through the sheet metal without pre-drilling to form a punch hole by pressure exerted on the punch rivet from above and then sheet material with plastic deformation into the Circumferential groove is pressed, characterized in that with the punch rivet the sheet material is displaced in a first annular area surrounding the punch hole in the punching direction, that the sheet material is then pushed upwards on the punch rivet by a counterforce exerted from below, and then the punch rivet is pushed through the punch hole is pressed further down until the

Head rests with its flat surface on the sheets, and that finally the sheet material displaced in the punching direction is plastically deformed into the circumferential groove by the counterforce.