DE102012017289A1 - Stamping element, useful in fastening arrangement for resistance welding of joining members e.g. sheet metal parts, comprises head element and shaft element having annular contour located at its one end facing away from end of head element - Google Patents

Abstract

The stamping element comprises a head element and a shaft element (23). The shaft element has an annular contour (31) located at its one end facing away from an end of the head element. The stamping element forms a contact zone on joining members that are driven by predetermine force. The annular contour is a hollow cylinder formed with a front side (30), which is present in surface contact or line contact with the joining members. The shaft element has an annular circumference, an acute angle or an obtuse angle, or a circularly protruding supporting edge. The stamping element comprises a head element and a shaft element (23). The shaft element has an annular contour (31) located at its one end facing away from an end of the head element. The stamping element forms a contact zone on joining members that are driven by predetermine force. The annular contour is a hollow cylinder formed with a front side (30), which is present in surface contact or line contact with the joining members. The shaft element has an annular circumference, an acute angle or an obtuse angle, or a circularly protruding supporting edge. The front side or the supporting edge continuously extends in a transverse plane of the shaft element. The annular supporting edge is formed in a front side of the shaft element and formed by running edges, and is present in a radial direction at a same level with an outer side (29) or inner side of the shaft element. The shaft element includes a recess such as radially encircling annular groove. During the connection operation, a material of joining members forms form-fit connection in the recess. Independent claims are included for: (1) a fastening arrangement; and (2) a device for connecting a stamping element with joining member.

Description

The invention relates to an embossing element in particular for resistance welding according to the preamble of claim 1, a fastening arrangement with such an embossing element according to claim 9 and a device for connecting the embossing element with a joining partner according to claim 10. Such an embossing element can be exemplified as a rivet in a punch riveting method are used.

In lightweight structures used in the automotive industry, the use of aluminum-steel joints is known in which, for example, an aluminum sheet metal part is connected to a steel sheet metal part. To connect these two sheet metal parts, a steel stamping element can first be driven into the aluminum sheet metal part. Subsequently, the driven in the aluminum sheet metal part steel stamping element can be connected by spot welding to the steel sheet metal part.

On the DE 2009 035 338 A1 Such a punch riveting method is known in which the steel rivet element can be placed on an aluminum sheet metal part and can be driven by the aluminum sheet metal part with a predetermined press-in force. The rivet element has a rivet head and a rivet shank. After driving in, the rivet element protrudes with its rivet shank out of the aluminum sheet metal part by a predetermined projection. The protruding from the aluminum sheet metal part end of the rivet shank is then optionally spot-welded with the interposition of an adhesive layer with the steel sheet metal part.

According to the DE 10 2009 035 338 A1 the rivet shank of the rivet element has a cylindrical basic body made of solid material, which has at its end facing away from the rivet head of a cone-like tapered tip. In this way, during spot welding results in a centrally located on the rivet element longitudinal axis Aufsetzpunkt, which is in terms of a perfect weld connection advantage.

In the case of the rivet element geometry set out above, however, an eccentric, ie eccentric, introduction of force when the rivet element is driven into the aluminum sheet metal part can lead to problems. If the introduction of force does not occur in alignment with the longitudinal axis, but eccentrically by a transverse offset, a lever arm results between the force introduction point and the longitudinal axis. As a result, the rivet element is subjected to a tilting moment directed around the seating point. This can lead to a gap formation between the rivet element head and the aluminum sheet metal part with the known corrosion problems. In addition, results from the optionally one-sided rivet element head an interference contour, which can lead to problems in the further manufacturing process.

The object of the invention is to provide an embossing element for resistance welding, a fastening arrangement with such an embossing element and a device for connecting the embossing element with the joining partner, in which a perfect component connection is ensured in a simple manner.

The object is solved by the features of claim 1, claim 9 or claim 10.

The embossing element according to the invention will be described below as a rivet element, especially when used in a stamped riveting method. It is understood, however, that the embossing element is not limited to the punch riveting method. Thus, the invention is based on the fact that in the above rivet element geometry with only a punctiform tip at the lower end of the rivet element coaxial to the rivet longitudinal axis force application in punch riveting is mandatory, but often only with a correspondingly high manufacturing complexity is possible. Against this background, according to the characterizing part of patent claim 1, the rivet shank of the rivet element according to the invention has a special ring contour at its end remote from the rivet head. With the ring contour, the rivet element can be placed on the joining partner to form an annular contact zone. Due to the annular contact zone, the rivet shank is no longer only punctiform supportable, but his Abstützbasis is increased accordingly. In this way, the punch riveting method is designed to tolerate more tolerable, with even an eccentric introduction of force with transverse offset is allowed without causing a tilting movement of the rivet element. In particular, the force introduction point can lie radially within the ring contour, without a tilting movement of the rivet element is to be feared.

The following aspects of the invention will be described for ease of understanding with reference to a particularly preferred connection of an aluminum sheet metal part with a steel sheet metal part by means of a steel rivet element. Accordingly, the first joining partner is the aluminum sheet metal part and the second joining partner is the steel sheet metal part. It is understood, however, that the following aspects of the invention, regardless of this particular material pairing, generally apply to any other joining partner.

In one embodiment, in order to form the ring contour of the rivet shank, at least in its region facing away from the rivet head, a hollow cylinder with an annular end face may be formed. Depending on the geometry, the annular end face can be brought into surface contact or in line contact with the aluminum sheet metal part or the steel sheet metal part. With regard to a perfect welding connection, line contact of the ring contour with the joining partner is advantageous.

To realize such a line contact, the rivet shank for forming the ring contour at its, the rivet head end remote from an annular peripheral support edge, which projects at an acute angle or obtuse angle in the axial direction. So that the ring contour results in a stable support base for the rivet element, it can preferably run continuously in a transverse plane of the rivet shank. The above-described annular support edge may also be formed directly in the end face of the rivet shank facing away from the rivet head. For this purpose, the annular bearing edge may be formed by mutually running flanks. The annular support edge may be to further improve the support base preferably in the radial direction at the same height as the outside of the rivet shank. In this case, the annular bearing edge is arranged in axial extension to the outside of the rivet shank. Alternatively, the annular bearing edge can also be at the same height as the inside of the hollow cylindrical rivet shank.

It is particularly preferred if, after the punching riveting process has taken place, the rivet element is fastened captive in the aluminum sheet metal part. To provide such a captive securing, the rivet shank may have a recess on the outside, in particular a radially encircling annular groove. When connecting the rivet element to the aluminum sheet metal part, aluminum material can be displaced into the recess to form a positive connection.

As mentioned above, the rivet element is initially placed on the aluminum sheet metal part during punching riveting and driven into the aluminum sheet metal part with a predetermined press-in force. After the driving in, the rivet element can protrude beyond the rivet head side of the aluminum sheet metal part with a predetermined projection. The protruding from the aluminum sheet metal part end of the rivet shank is then optionally welded with the interposition of an adhesive layer with the steel sheet metal part, wherein the weld lens is preferably not point-like, but annular. With the help of the adhesive layer is also ensured that an electrolytic contact between the aluminum sheet metal part and the steel sheet metal part is prevented.

The device for carrying out a punching-riveting method according to the invention has a punch with which the rivet element can be driven through the aluminum sheet-metal part. In addition, the device has a die, which is positioned as an abutment on the side facing away from the stamp side of the aluminum sheet metal part. The punched in driving the steel rivet in the aluminum sheet metal part can be removed through a passage of the die, in which the rivet shank of the rivet element is retractable with its lower end.

The following is a special geometry of the die described to hold the steel rivet element captive in the aluminum sheet metal part. Accordingly, the passage of the die is annular, namely radially bounded by an outer hollow cylindrical inner wall of the die and a radially inner cone. The cone expands in the direction of retraction of the rivet element and can optionally be dimensioned so that the ring contour abuts the cone surface during retraction and is spread apart.

Alternatively / or additionally, the die may have at least one projection on its support facing the aluminum sheet metal part. The projection is pressed during punch riveting in the aluminum sheet metal part, whereby aluminum material is displaced, and thereby correspondingly increases the clamping forces acting on the rivet shank. Preferably, the projection is formed directly on the passage edge of the die.

The die formed with the projection is effective, in particular in combination with the radially outer recesses in the rivet shank. In this case, namely, the aluminum material can be displaced into the radially outer recesses of the rivet shank, resulting in a positive connection between the rivet and the aluminum sheet metal part.

The advantageous embodiments and / or further developments of the invention explained above and / or reproduced in the dependent claims can be used individually or else in any desired combination with one another, for example in the case of clear dependencies or incompatible alternatives.

The invention and its advantageous embodiments and / or developments and their advantages will be explained in more detail with reference to the drawing.

Show it:

1 to 5 in each case roughly schematic views for illustrating a punching Riveting with subsequent resistance. welding;

6 in an enlarged view of an inventive rivet element in side sectional view;

7 to 9 each possible different contours in the foot of the rivet element;

10 a known from the prior art rivet to describe the problem solved by the invention;

11 a side view of a die in full section; and

12 in an exploded view of a rivet, an aluminum sheet metal part and a die according to another embodiment.

The stamping element according to the invention three is shown in the figures by way of example as a rivet element for use in a stamped riveting method. So is special in the 1 to 5 a punching-riveting method with downstream resistance spot welding roughly schematically illustrated insofar as it is necessary for understanding the invention. Accordingly, in the, in the 1 to 5 illustrated method steps an aluminum sheet metal part 1 with the help of a steel rivet element three with a steel sheet metal part 5 connected. For this purpose, the first 1 the rivet elements three on the aluminum sheet metal part 1 placed and, for example, by means of a not shown pressing tool with a predetermined pressing force F _P through the material of the aluminum sheet metal part 1 driven through. The resulting from the aluminum sheet metal part 1 punched slugs 5 ( 2 ) is through a passage 7 an acting as an abutment die 9 dissipated. During the press-fitting process is the aluminum sheet metal part 1 with its bottom 11 on a support 13 the matrix 9 supported.

After the press-in process protrudes in accordance with the three the rivet element three with a supernatant a from the, from the rivet head 15 opposite side 11 of the aluminum sheet metal part 1 out, with one, the rivet head 15 opposite end 17 , Subsequently, according to the 4 and 5 the cohesive connection with the steel sheet metal part 5 , For this purpose, the steel sheet metal part 5 at its contact surface with an adhesive layer 19 provided and that from the aluminum sheet metal part 1 overhanging end 17 of the rivet element three in contact with the steel sheet metal part 5 brought. This is followed by conventional resistance spot welding technology 17 of the rivet element three forming a weld nugget 21 with the steel sheet metal part 5 welded.

Based on 6 is the special geometry of the steel rivet element according to the invention three described. Consequently, the rivet element three next to the rivet head 5 one through the aluminum sheet metal part 1 to be driven rivet 23 on, according to the 6 hollow cylindrical (also semi-hollow is conceivable) with a bore 25 is executed. The rivet element three is a trained about a longitudinal axis A rotationally symmetrical steel body. Its riveting 23 has a cylindrical outside 29 on, which is an outer radius r from the longitudinal axis A of the rivet element three is spaced.

Due to the hollow cylindrical design of the rivet shank 29 results from his, the rivet head 15 opposite end 17 a ring contour 31 with which the rivet element three forming an annular contact zone K ( 1 and 4 ) on the aluminum sheet metal part 1 and on the steel sheet metal part 5 can be placed. Due to the ring contour 31 is the nugget 21 ( 5 ) between the rivet element three and the steel sheet metal part 5 not punctiform but annular.

The ring contour 31 of riveting 23 is in the 6 through an annular end face 30 formed, which runs continuously in a transverse plane to the longitudinal axis A. The front side 30 is in each case in surface contact with the aluminum sheet metal part 1 as well as the steel sheet metal part 5 brought.

The in the 6 illustrated special geometry of the rivet shank 23 gives a comparison to known rivet elements (see for example the 10 ) substantially enlarged and thus more stable support base, which is particularly advantageous for an eccentric force introduction of the press-in force. Exemplary are in the 6 Arrows indicate a centric introduction of force F _p1 and two eccentric force inputs F _p2 and F _p3 . In the case of eccentric force introduction, the force introduction point is a transverse offset Δy ₂ or Δy ₃ (FIG. 6 ) offset radially from the longitudinal axis A. The transverse offset Δy ₂ is smaller than the outer radius r of the rivet shank 23 , Which results in the eccentric force F _P2 no lever arm and thus no tilting moment with which the rivet element three could tip over.

By contrast, the transverse offset Δy ₃ in the case of the eccentric force introduction F _p3 is greater than the outer radius r of the rivet shaft 23 , This results between the outside 29 and the force application point F _p3 , a lever arm h. In contrast to the invention (cf. 10 ) However, the lever arm h and thus the resulting tilting moment is so low that tilting of the rivet element three is to be feared.

In the following 7 to 9 are in enlarged detail views alternative ring contours 31 shown. So is in the 7 at the flat front side 30 a projecting in the axial direction and annular peripheral bearing edge 32 formed. The bearing edge 32 is in the 7 by isosceles to each other running flanks 33 . 34 formed and approximately between the outer wall 29 and the inner wall 27 of the hollow cylindrical rivet shank 23 arranged in the middle. Accordingly, the in the 7 shown annular peripheral support edge 33 executed at an obtuse angle ..

Instead, in the 8th and 9 each ring contours 31 with acute-angled, annular peripheral edges 32 shown. In the 8th is the inside flank 33 in the axial direction A in alignment with the inner wall 27 executed. The acute-angled bearing edge 32 is therefore, considered in the radial direction, at the same height with the inner wall 27 of riveting 23 arranged.

The in the 9 shown ring contour 31 an acute-angled, annular peripheral bearing edge 32 on, whose radially outer edge 34 in flight with the outside 29 of riveting 23 is extended. Accordingly, in the 9 the acute-angled bearing edge 32 , viewed in the radial direction, at the same height as the outside 29 of riveting 23 arranged. The support base thus formed is therefore compared to 7 and to 8th even further increased. Alternatively, not only acute-angled but also round geometries are possible.

In the 10 is a known from the prior art rivet element three to illustrate the problem solved by the invention. In contrast to the invention, the rivet element three according to the 10 a cylindrical rivet shank 23 made of solid material, on his, the rivet head 15 opposite end 17 conical on a, located on the longitudinal axis A cone tip 39 tapers. The compared to the ring contour 31 from the cone tip 39 Provided support base is thus only punctiform and thus much lower than in the invention. The low support base has in particular at a in the 10 indicated eccentric force introduction of the pressing force F _p impact. In such an eccentric introduction of force of the force application point is again spaced by a transverse offset Δy from the longitudinal axis A. The transverse offset Δy corresponds to a lever arm with which the rivet element three is tilted with a tilting moment M _K. Due to the significantly reduced compared to the invention support base leads the eccentric force introduction inevitably to a tilting of the rivet element three (indicated by the dash-dotted lines), which leads to connection errors between the element three and the steel part or in general can lead to connection errors in the sheet metal part connection.

In the 11 and 12 are each special geometries of the die 9 described with their help the steel rivet element three captive in the aluminum sheet metal part 1 can be held. Consequently, according to the 11 the passage 7 the matrix 9 designed annular, and although radially bounded by an outer hollow cylindrical inner wall 43 the matrix 9 and a radially inner cone 45 , The cone 45 widens in the retraction direction of the rivet element three from and is dimensioned so that during retraction the ring contour 31 strikes the cone surface and is spread.

In the 12 has the die 9 on her, the aluminum sheet metal part 1 facing support 13 an example of a circular ring 47 on, at the opening edge of the passage 7 is formed. The circular ring 7 is punched in the aluminum sheet metal part 1 pressed. This turns aluminum material into the radially outer annular groove 41 of riveting 23 shifted in, resulting in between the rivet element three and the aluminum sheet metal part 1 a positive connection results.

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 2009035338 A1 [0003]
• DE 102009035338 A1 [0004]

Claims (12)

Imprinting element for resistance welding, which is applied to at least one joining partner ( 1 . 5 ), in particular a sheet metal part, can be placed and with a predetermined force (F _P ) by the joining partner ( 1 . 5 ), which impressing element ( three ) an element head ( 15 ) and an elementary ( 23 ), characterized in that the element shaft ( 23 ) of the impressing element ( three ) at its the element head ( 15 ) facing away from the end ( 17 ) an annular contour ( 31 ), with which the imprinting element ( three ) forming an annular contact zone (K) on the joining partner ( 1 . 5 ) can be placed. An embossing element according to claim 1, characterized in that for the formation of the ring contour ( 31 ) of the elementary ( 23 ) at least at its the element head ( 15 ) facing away from the end ( 17 ) hollow cylindrical with an annular end face ( 30 ) which is in surface contact or in line contact with the joining partner ( 1 . 5 ) bring bar is. An embossing element according to claim 1 or 2, characterized in that the element shaft ( 23 ) for forming the ring contour ( 31 ) at its the element head ( 15 ) facing away from the end ( 17 ) an annular circumferential, acute-angled or obtuse-angled or round projecting bearing edge ( 32 ) having. An embossing element according to one of claims 1, 2 or 3, characterized in that the ring contour ( 31 ), in particular the front side ( 30 ) or the annular support edge ( 32 ), consistently in a transverse plane of the elementary ( 23 ) runs. Einprägeelement according to claim 3 or 4, characterized in that the annular bearing edge ( 32 ) on the front side ( 30 ) of the elementary ( 23 ) is trained. An embossing element according to any one of claims 3, 4 or 5, characterized in that the annular bearing edge ( 32 ) by mutually running flanks ( 33 . 34 ) is formed, and / or that the annular bearing edge ( 32 ) in the radial direction at the same level with the outside ( 29 ) or with the inside ( 27 ) of the elementary ( 23 ) lies. An impressing element according to one of the preceding claims, characterized in that the element shaft ( 23 ) radially on the outside at least one recess ( 41 ), in particular a radially encircling annular groove, and that during the joining process the material of the joining partner ( 1 ) to form a positive connection in the recess ( 41 ) is hineinverlagerbar. Fastening arrangement with an embossing element ( three ) according to one of the preceding claims and a joining partner ( 1 ), wherein the impressing element ( three ) after pressing into the joining partner ( 1 ) with a predetermined projection (a) from the element head ( 15 ) facing away ( 11 ) of the joining partner ( 1 ), and in particular that of the joint partner ( 1 ) outstanding end ( 17 ) of the elementary ( 23 ), optionally with the interposition of an adhesive layer ( 19 ), with a second joint partner ( 5 ) is weldable, in particular to form an annular weld nugget ( 21 ). Device for connecting an embossing element ( three ), in particular according to one of claims 1 to 7, with a joining partner ( 1 ), with a stamp, with which the impressing element ( three ) by the joining partner ( 1 ) is drivable, and a die ( 9 ), which act as an anvil on the side facing away from the stamp ( 11 ) of the joining partner ( 1 ) is positioned, the die ( 9 ) for discharging a punched-out ( 5 ) a passage ( 7 ) into which the elementary ( 23 ) with its the element head ( 15 ) opposite end ( 17 ) is retractable. Device according to claim 9, characterized in that the passage ( 7 ) of the die ( 9 ) is annular and by a radially outer hollow cylindrical inner wall ( 43 ) of the die ( 9 ) and by a radially inner cone ( 45 ) is limited, which in the retraction direction of the embossing element ( three ) and with which the ring contour ( 31 ) of the elementary ( 23 ) is spreadable. Device according to claim 10 or 11, characterized in that the die ( 9 ) on their joint partner ( 1 ) facing supports ( 13 ) at least one projection ( 47 ), with which during the press-fitting process the material of the joining partner ( 1 ) by increasing on the elementary ( 23 ) acting clamping forces is displaced. Apparatus according to claim 11, characterized in that in the case of radially outer recesses ( 41 ) in elementary ( 23 ) the material of the joining partner ( 1 ) to form a positive connection in the wells ( 41 ) is hineinverlagerbar.

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