WELDING AUXILIARY JOINING PART

Abstract

A welding auxiliary joining part with which a welding connection, more particularly a resistance welding connection, can be established between a first component A made of a poorly weldable material and a second component made of weldable material. The welding auxiliary joining part is distinguished by a cylindrical punch shaft that can be punchingly pressed into the first component A approximately rotation-free. The punch shaft has an element head at the head underside of which only one continuous circumferential clamping ring is arranged that projects axially in the direction of the punch shaft.

Claims

1. A welding auxiliary joining part with which a welding connection is establishable between a first component of poorly weldable material and a second component of weldable material, which comprises the following features: a. a punch shaft which is punchingly pressable into the first component approximately rotation-free, which extends along a longitudinal axis of the welding auxiliary joining part and which has an element head at a first axial end and a welding contact zone projecting in the axial direction from the punch shaft at a second axial end, b. the element head extends radially beyond the punch shaft and comprises a head upper side facing away from the shaft and a head underside facing towards the shaft, which are connected to one another by means of a circumferential face which radially delimits the element head, and in which c. the head underside comprises at least one first clamping ring which extends around the punch shaft in a closed manner and projects axially in the direction of the punch shaft, c1. which is arranged at a first radial distance from the punch shaft, c2. which has a triangular-like cross-sectional shape which tapers in the axial direction of the punch shaft, and c3. which is arranged at a side facing away from the punch shaft radially spaced from the circumferential face of the element head.

2. Welding auxiliary joining part according to claim 1, in which the clamping ring is surrounded at the side facing away from the punch shaft by a radially extending outer ring face and/or by at least one outer ring at the head underside, which outer ring extends around the punch shaft in a closed or interrupted manner and projects axially in the direction of the punch shaft.

3. Welding auxiliary joining part according to claim 2, in which the outer ring has the shape of a clamping ring or a stamping ring.

4. Welding auxiliary joining part according to claim 1, in which the clamping ring is arranged at the side facing the punch shaft adjacent to a radially extending inner ring face at the head underside and/or adjacent to at least one inner ring at the head underside which extends around the punch shaft in a closed or interrupted manner and projects axially in the direction of the punch shaft.

5. Welding auxiliary joining part according to claim 4, in which the at least one inner ring has the shape of a clamping ring or of a stamping ring.

6. Welding auxiliary joining part according to claim 1, in which the axial cross-sectional shape of the clamping ring is formed by a radially inner ring side and a radially outer ring side, the inner ring side of which encloses with the punch shaft an inclination angle in the range of 1070.

7. Welding auxiliary joining part according to claim 6, in which the outer ring side encloses with the head underside an angle in the range of 70110.

8. Welding auxiliary joining part according to claim 1, in which the cross-sectional shape of at least one clamping ring is approximated to a right-angled triangle, the hypotenuse of which faces the punch shaft.

9. Welding auxiliary joining part according to claim 3, in which the stamping ring comprises a spherical cross-sectional shape.

10. Welding auxiliary joining part according to claim 1, which has at the head underside only one clamping ring which extends around the punch shaft in a closed manner and which is arranged at a first radial distance from the punch shaft, and which has a triangular cross-sectional shape, which tapers in the axial direction of the punch shaft and which has at a side facing away from the punch shaft a radially extending outer ring face at the head underside which transitions into the circumferential face of the element head.

11. Welding auxiliary joining part according to claim 1, which comprises a groove at the head underside between the punch shaft and the adjacent clamping ring or an adjacent stamping ring, which groove is recessed in the direction of the element head.

12. Welding auxiliary joining part according to claim 11, in which the element head has a greater thickness in the longitudinal direction of the punch shaft in the portion of the groove than outside of the groove and the clamping ring and/or the stamping ring.

13. Welding auxiliary joining part according to claim 1 in which a ratio of a head diameter of the element head to a shaft diameter of the cylindrical punch shaft is greater than or equal to two.

14. Welding auxiliary joining part (1) according to claim 1 in which a shaft diameter D.sub.10 of the punch shaft compared to an outer diameter D.sub.40 of the clamping ring is approximately 0.5 D.sub.40D.sub.100.8 D.sub.40.

15. Welding auxiliary joining part (1) according to claim 1, in which the punch shaft has a shaft diameter D.sub.10 in the range of 3 mmD.sub.108 mm, the element head has a head diameter D.sub.30 in the range of 7 mmD.sub.3012 mm, and the clamping ring has a ring diameter D.sub.40 in the range of 4 mmD.sub.4010 mm.

16. Welding auxiliary joining part according to claim 1, in which the element head has an axial thickness H.sub.30 between the head upper side and the head underside outside of a groove or ring in the range of 0.8 mmH.sub.301.8 mm, and the punch shaft has a length h.sub.10 in the range of 1.6 mmh.sub.104 mm.

17. Welding auxiliary joining part according to claim 1, in which the clamping ring has a height H.sub.40 with respect to the head underside in the range of 0.2 mmH.sub.400.6 mm.

18. Welding auxiliary joining part according to claim 1, in which the clamping ring has a height H.sub.40 with respect to the head underside in the range of 0.15 mmH.sub.401 mm.

19. Welding auxiliary joining part according to claim 1, in which the element head is formed as a countersunk head at least radially outwardly from the clamping ring, has a radially outwardly decreasing axial thickness H.sub.30 between the head upper side and the head underside outside of a groove or ring in the range of 0.3 mmH.sub.300.8 mm, and the punch shaft measured between the free shaft end and the radially outermost head underside has a length h.sub.10 in the range of 1.4 mmh.sub.103 mm.

20. Welding auxiliary joining part according to claim 1, in which the clamping ring has a height H.sub.40 with respect to the head underside adjacent to the clamping ring in the range of 0.2 mmH.sub.401 mm.

21. Welding auxiliary joining part according to claim 11, in which the groove has a depth t.sub.50 in comparison with a height of an immediately adjacent clamping ring or stamping ring in the range of 0.2 mmt.sub.500.6 mm.

22. Welding auxiliary joining part according to claim 1, in which the welding contact zone is formed by a welding stud having a smaller radial extent than the punch shaft or by a convex welding projection having the same radial extent as the punch shaft.

23. Component composite comprising at least a first component and a welding auxiliary joining part according to claim 1, which is fastened in the first component in a loss-proof manner.

24. Component composite according to claim 23, in which the first component has a thickness D.sub.A in the range of 0.8 mmD.sub.A3 mm.

25. Component composite according to claim 23, in which the element head has a thickness H.sub.30 in the range 0.5 D.sub.AH.sub.302 D.sub.A and the clamping ring has a height H.sub.40 and a diameter D.sub.40 in the ranges 0.2 D.sub.AH.sub.400.5 D.sub.A and 3 D.sub.AD.sub.4010 D.sub.A and the punch shaft has a length h10 in the range 1.1 D.sub.Ah.sub.102 D.sub.A.

26. Component composite according to claim 23, in which the first component is welded to a second component by means of the welding auxiliary joining part.

27. Manufacturing method of a component composite of at least a first component and the welding auxiliary joining part according to claim 1, which comprises the following steps: a. providing the first component, b. pressing the welding auxiliary joining part into the first component approximately rotation-free, so that the punch shaft completely penetrates the component, the welding contact zone projects beyond a component side facing away from the element head, and the element head abuts against a component side facing the element head and the clamping ring is thereby stamped into the component side facing the element head.

28. Manufacturing method according to claim 27, with the further step: c. arranging the first component with the welding auxiliary joining part above a second component in such a manner that an electrical contact is establishable between the welding contact zone of the punch shaft and the second component, and d. resistance welding the welding auxiliary joining part and the second component.

29. Manufacturing method according to claim 27, in which the welding auxiliary joining part is fastened in a loss-proof manner in the first component after pressing-in, and the first component is present as a semi-finished product, and resistance welding of the semi-finished product with the second component at the place of manufacture of the pressing-in and/or after intermediate storage of the semi-finished product after pressing-in or after transport from the place of manufacture of the pressing-in to a processing place for resistance welding.

30. Manufacturing method according to claim 27, wherein pressing the clamping ring into the first component displaces a material portion of the first component radially inwards so that the punch shaft is clamped by the displaced material.

31. (canceled)

Description

4. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0046] Some embodiments of the present disclosure are described in more detail with reference to the accompanying drawing. Showing in:

[0047] FIG. 1 a partial cross-sectional view of an embodiment of the welding auxiliary joining part,

[0048] FIG. 2 a sectional enlargement of the encircled portion of FIG. 1,

[0049] FIG. 3 a partial sectional view of a further embodiment of the welding auxiliary joining part with countersunk head,

[0050] FIG. 4 a sectional enlargement of the encircled portion of FIG. 5,

[0051] FIG. 5 a sectional enlargement of a further embodiment of the underside of the element head with a first and a second clamping ring,

[0052] FIG. 6 a sectional enlargement of a further design of an underside of the element head with a first and a second clamping ring,

[0053] FIG. 7 a sectional enlargement of a further design of the underside of the element head with a clamping ring and a stamping ring arranged radially outwards thereof,

[0054] FIG. 8 a sectional enlargement of a further design of the underside of the element head with a clamping ring and a stamping ring arranged radially outwards thereto,

[0055] FIG. 9 a sectional enlargement of a further design of the underside of the element head with a stamping ring and a clamping ring arranged radially outwards thereof,

[0056] FIG. 10 a sectional enlargement of a further design of the underside of the element head with a stamping ring and a clamping ring arranged radially outwards thereto,

[0057] FIG. 11 a sectional enlargement of a further design of the underside of the element head with a first and a second clamping ring and a stamping ring arranged radially outwards thereto,

[0058] FIG. 12 a sectional enlargement of a further design of the underside of the element head with a first and a second clamping ring and a stamping ring arranged radially outwards thereto,

[0059] FIG. 13 a sectional enlargement of a further design of the underside of the element head with a clamping ring arranged radially inwards, a stamping ring arranged radially outwards thereto and a further clamping ring arranged radially outwards to the stamping ring,

[0060] FIG. 14 a further embodiment of a design of the underside of the element head with a clamping ring arranged radially inwards, a stamping ring arranged radially outwards thereto and a further clamping ring arranged radially outwards,

[0061] FIG. 15 a sectional enlargement of a further design of the underside of the element head with a stamping ring arranged radially inside, which is surrounded by two clamping rings arranged radially outside,

[0062] FIG. 16 a sectional enlargement of a further design of the underside of the element head with a stamping ring arranged radially inside and two clamping rings surrounding it,

[0063] FIG. 17 a sectional enlargement of a further embodiment of a design of the underside of the element head with a stamping ring arranged radially inside and a further stamping ring arranged radially outside and a clamping ring arranged between the two stamping rings, and

[0064] FIG. 18 a sectional enlargement of a further design of the underside of the element head with a first stamping ring arranged radially inwards and a second stamping ring arranged radially outwards and a clamping ring arranged between the stamping rings.

5. DETAILED DESCRIPTION

[0065] FIG. 1 shows an embodiment of the welding auxiliary joining part 1 in a partial sectional view. The welding auxiliary joining part 1 is made of known weldable materials which are selected according to the welding method used. With regard to the used resistance spot and projection welding, alloy steels may be suitable. However, other materials may also be used here.

[0066] The welding auxiliary joining part 1 comprises a punch shaft 10 which extends parallel to a longitudinal axis L of the welding auxiliary joining part 1. The punch shaft 10 is designed to be pressed or punched into a first component A approximately rotation-free. The welding auxiliary joining part 1 is self-punching, so that the welding auxiliary joining part 1 is pressable or punchable into non-pre-punched components as well as into pre-punched components. Accordingly, the welding auxiliary joining part 1 may be configured as a solid punch rivet in order to ensure time-saving and reliable joining into a component A. As solid punch riveting is known in the prior art, the setting tools used for solid punch riveting may also be used for setting the welding auxiliary joining part 1.

[0067] As can be seen from the schematic illustration in FIG. 1, the welding auxiliary joining part 1 may be formed rotationally symmetrically about its longitudinal axis L. Here, the punch shaft 10 has a cylindrical shape and may have a diameter D.sub.10 in the range of 3 mmD.sub.108 mm, or 4 mmD.sub.105 mm and D.sub.10 may be 4 mm or D.sub.10 may be 5 mm. The cylindrical shape is distinguished by a smooth lateral face 12. The lateral face 12 may have retaining ribs or retaining rings (not shown) extending transversely to the longitudinal axis L, which support a fastening of the punch shaft 10 in a component opening. As an alternative to the cylindrical shape of the punch shaft 10, the latter has the shape of a truncated cone which expands in the joining direction. It may also be preferred that the punch shaft 10 is not shaped rotationally symmetrically in cross-section. By this, a form-fit against relative rotation between component A and welding auxiliary joining part 1 is realized.

[0068] The punch shaft 10 comprises a welding contact zone 60 at its free axial end. The welding contact zone 60 extends beyond a length L.sub.10 of the punch shaft 10 in order to establish an electrical contact with the second component to be welded during the resistance welding. The design of the welding contact zone 60 is described in more detail below.

[0069] An element head 30 is provided at the second axial end of the punch shaft 10, which is integrally formed with the punch shaft 10. The element head 30 comprises a head upper side 32, which may be formed in a flat manner. It also serves as a contact face for a punch (not shown), which presses the welding auxiliary joining part 1 into the component A.

[0070] Adjacent to the punch shaft 10, the element head 30 comprises a head underside 34. The head underside 34 is connected to the head upper side 32 via a circumferential face 36. The circumferential face 36 may form a cylindrical lateral face of the element head 30. Accordingly it defines the diameter of the element head 30 and extends along an outline of the element head 30. The element head 30 may have a diameter D.sub.30 in the range of 7 mmD.sub.3012 mm, such as D.sub.30=10 mm. Furthermore, it may have a height H.sub.30 in the range of 0.8 mmH.sub.301.8 mm, such as H.sub.30=1.2 mm. With respect to the punch shaft 10, the element head 30 has a diameter of D.sub.301.4.Math.D.sub.10.

[0071] If it is advantageous, the circumferential face 36 may also be shaped differently. For example, it may have the shape of a lateral face of a truncated cone if the element head 30 is formed as a countersunk head. It could also be completely omitted if the head upper side 32 forms a round head which transitions directly into the underside 34.

[0072] It may also be preferred that the element head 30 has a truncated cone shape, a truncated pyramid shape or a polyhedron shape instead of the cylindrical shape shown in FIG. 1. However, the cylindrical shape is advantageous for a setting process using a joining device, since the cylindrical circumferential face 36 represents a supporting guide face in a joining channel of the joining device.

[0073] A clamping ring 40 is arranged at the head underside 34 of the element head 30 concentrically to the longitudinal axis L and to the punch shaft 10. The clamping ring 40 may protrude in the axial direction from the head underside 34. According to an embodiment, only one clamping ring 40 is provided at the otherwise flat head underside 34. This ensures an unhindered radial material flow radially inwards and radially outwards, which is not diverted or blocked by a further clamping ring or stamping ring (see below).

[0074] The clamping ring 40 may have a triangular cross-sectional shape, as can be seen from the dashed lines in FIG. 2. FIG. 2 shows a sectional enlargement of the encircled portion of FIG. 1.

[0075] The cross-sectional shape of the clamping ring 40 is defined by a radially inner ring side 42 and a radially outer ring side 44. The ring sides 42, 44 in combination with the head underside 34 define a triangular cross-sectional shape of the clamping ring 40. The clamping ring 40 is arranged at a first radial distance from the circumferential face 12 of the punch shaft 10, which is described in more detail below. The clamping ring 40 is surrounded radially outwards by a ring face 38, which forms a part of the head underside 34. The ring face 38 may be formed flat and perpendicular to the longitudinal axis L. In addition, the ring face 38 transitions into the circumferential face 36, whereby the head underside 34 and the head upper side 32 are connected to each other.

[0076] In order to be able to weld the first component A made of poorly weldable material, such as plastic or aluminum, to the second component made of weldable material, the welding auxiliary joining part 1 is pressed or punched into the first component A. The component A may have a thickness D.sub.A in the range of 0.8 mmD.sub.A3 mm, such as D.sub.A=1.5 mm. For this, the first component A supports itself on a die, such as with a central opening (not shown). In order to simplify the setting process as much as possible, the welding auxiliary joining part 1 is pressed into the first component A without rotation. For this, a setting punch applies a joining force to the head upper side 32 and presses the welding auxiliary joining part 1 with the punch shaft 10 first into the component A. Thereby an opening is created in the component A, so that the welding contact zone 60 at the side of the component A facing away from the head protrudes beyond this component side (see FIG. 1). Accordingly, the length h.sub.10 of the punch shaft 10 is adapted to the thickness D.sub.A of the component A. It may be preferred that the length h.sub.10 of the punch shaft 10 is 1.1 D.sub.Ah.sub.102 D.sub.A, or 1.4 D.sub.Ah.sub.101.8 D.sub.A. The punch shaft 10 may have a length h.sub.10 in the range of 1.6 mmh.sub.104 mm, in particular h.sub.10=2 mm. In addition, the element head 30 may have a height H.sub.30 with respect to the component thickness D.sub.A of 0.5 D.sub.AH.sub.302 D.sub.A, such as H.sub.30=D.sub.A applies.

[0077] During the setting process, the welding auxiliary joining part 1 is pressed into the component A until at least the head underside 34 with the ring face 38 abuts the component side facing the head. It may also be preferred to press the element head 30 deeper into the component A, so that a part of the element head 30 is received in the component A. During this setting process, the clamping ring 40 is also pressed into the component A.

[0078] The radially inner ring side 42 is arranged at an angle inclined relative to the lateral face 12 or the longitudinal axis L. Since the ring side 42 is arranged at an angle <90 relative to the circumferential face 12, the ring side 42 displaces material of the component A in the direction of the punch shaft 10 when it is pressed into component A. Especially the radial part of the displaced component material presses against the punch shaft 10 and provides an additional clamping effect and holding force of the punch shaft 10 in the component A due to mechanical radial stresses. The clamping effect increases with increasing radially inwardly directed material displacement. Therefore, the ring side 42 may be arranged in an angle range of 1070, such as 4060, in particular =45 or =50.

[0079] The clamping effect increases with the displaced material volume in the direction of the punch shaft 10. The amount of the material volume is determined by the volume of the clamping ring 40, which protrudes beyond the head underside 34. It may be preferred to vary a height H.sub.40 of the clamping ring 40 for the purpose of forming the displaced material volume. The height H.sub.40 of the clamping ring 40 indicates the distance with which the clamping ring 40 protrudes at a maximum beyond the head underside 34 (see FIG. 1). The clamping ring 40 may have a height H.sub.40 in the range of 0.2 mmH.sub.400.6 mm, such as H.sub.40=0.4 mm.

[0080] According to a further embodiment, the clamping ring 40 has a height H.sub.40 in the range of 0.15 mmH.sub.401 mm, such as H.sub.40=0.5 mm. With this height variation, the clamping ring is flexibly adaptable to both larger and smaller sheet thicknesses in comparison to the previously described embodiment.

[0081] Furthermore, the clamping ring 40, which extends concentrically around the punch shaft 10, may have an outer diameter D.sub.40 in the range of 4 mmD.sub.4010 mm, such as D.sub.40=8 mm. With regard to the component A and may be adapted to its dimensions, for the clamping ring 40 the following applies: 0.2.Math.D.sub.AH.sub.400.5 D.sub.A and 3.Math.D.sub.AD.sub.4010.Math.D.sub.A. With respect to the punch shaft 10, 0.5.Math.D.sub.40D.sub.100.8.Math.D.sub.40 may apply.

[0082] The clamping effect is determined by the displaced material of component A pressing radially inwards against the punch shaft 10. For this, the displaced material may be forced into an intermediate space 50 between the lateral face 12 and the inner ring side 42. This intermediate space 50 may also be referred to as a groove, which is arched in the direction of the element head 30.

[0083] In order to reduce this intermediate space 50 and thus increase the clamping effect due to displaced material, the intermediate space 50 has a base 52. The base 52 is a face segment which connects the lateral face 12 and the ring side 42 with each other. The base 52 may be arranged axially offset in the direction of the welding contact zone 60. Thus, the base 52 protrudes in the setting direction with respect to the ring face 38 and the head underside 36. In this way, the space for receiving radially inwardly displaced material may be selectively reduced and the clamping effect at the punch shaft 10 is improved. The depth t.sub.50 of the groove 50 with respect to the highest point of the adjacent clamping ring 40 (see FIG. 1) is in the range of 0.2 mmt.sub.500.4 mm, such as t.sub.50=0.3 mm. It may also be preferred to define the depth t.sub.50 of the groove 50 with respect to the height H.sub.40 of the clamping ring 40 with respect to the head underside 34. Therefore, 0.6.Math.H.sub.40t.sub.501.Math.H.sub.40 applies.

[0084] In order to stabilize the welding auxiliary joining part 1 in the component A, the radially outer ring side 44 is arranged at an angle in the range of 70110 with respect to the ring face 38. Due to the size of the angle the ring side 44 extends approximately in the setting direction. In this way, the ring side 44 creates radial stability for the welding auxiliary joining part 1 in the component A.

[0085] Referring to the cross-sectional shape of the clamping ring 40 and the size of the angles and , it may be preferred that the cross-sectional shape approximately comprises a right-angled triangle. Therefore the angle may be equal to 90. The hypotenuse of this triangular form faces the punch shaft 10 in order to cause an advantageous material flow radially inwards.

[0086] In addition, the fastening of the welding auxiliary joining part 1 in the component A may be influenced by the shape of the groove 50. It has been proven to be advantageous and therefore may be preferred if the outwardly delimiting wall of the groove 50 is formed on the one hand by the obliquely inclined side 42 of the clamping ring 40 and on the other hand by a vertical section v.sub.50 of the punch shaft 10. The vertical section v.sub.50 is a section of the lateral face of the punch shaft 10 which extends perpendicularly to the element head 30 or parallel to the longitudinal axis L of the welding auxiliary joining part 1. This section begins at the level of the clamping ring 40 and extends in the direction of the element head 30 until a connecting curvilinear connecting portion or area, such as a circular arc, begins between the vertical section v.sub.50 and the hypotenuse 42 of the clamping ring 40 (see FIG. 2). The support of the welding auxiliary joining part 1 in the component A may be supported with an increasing size of the vertical portion v.sub.50. Accordingly, the vertical portion v.sub.50 has a size of 0v.sub.500.3 t.sub.50, or v.sub.50=0.1 t.sub.50 or v.sub.500.2 t50.

[0087] If it is sufficient for holding the welding auxiliary joining part 1, the groove 52 is formed solely by the curvilinearally extending portion at the rivet base 52. In this case, the curvilinear portion ends at the level or height of the clamping ring 40, so that no vertical portion v.sub.50 is used in this embodiment.

[0088] Furthermore, the above-mentioned vertical section v.sub.50 may transition into the curvilinear rivet base 52 at an angle from the range of 4060, such as =50.

[0089] Opposite to the element head 30, the welding contact zone 60 is arranged at the punch shaft 10. According to a further embodiment, the welding contact zone 60 has the shape of a welding stud projecting axially from the punch shaft 10 or of a welding projection. These have a smaller diameter than the punch shaft 10. In addition, they have an arched, mostly rounded shape in order to establish a punctiform contact with the second component.

[0090] According to a further embodiment, the welding contact zone 60 is formed as a convex axial end of the punch shaft 10. This convex end arches in a circular arc at the end of the punch shaft 10 in the joining direction. This shaping also provides a sufficient, punctiform contact face with the second component for the resistance welding. Of course, a formed tip can also be used at this position.

[0091] A further embodiment of the welding auxiliary joining part 1 is shown in FIGS. 3 and 4. In this embodiment, the same reference signs for the element geometry described above also indicate the same features. These geometric features described above may therefore be transferred to the element geometry described here.

[0092] The welding auxiliary joining part 1 comprises a countersunk head as element head 30. The head underside 34 of the element head 30 may be arranged in its course radially outwardly inclined starting at the clamping ring 40. The inclination is present in the direction facing away from the shaft. Accordingly, the height H.sub.30 of the element head 30 is reduced radially outwards up to the circumferential face 36.

[0093] The countersunk head geometry makes it possible to lower the element head 30 into the component during the setting process. In this way, the interference contour of the element head 30 is reduced after the joining process. The element head 30 protrudes less than 0.4 mm from the component surface after setting in the component. Furthermore, the size of the contact face between the component and the underside 34 of the element head 30 may be increased. This allows the possibility to transfer heat via a larger interface between element and component during a later welding process. This can support a selective component heating or reduce a component damage of a smaller contact portion or area between element and component due to heat.

[0094] Due to the countersunk head geometry, the element head 30 may have a radially outward decreasing axial thickness H.sub.30 between the head upper side 32 and the head underside 34. Outside of the groove 50 or the clamping ring 40, the axial thickness H.sub.30 of the element head 30 may be in the range of 0.3 mmH.sub.300.8 mm, or 0.4 mmH.sub.300.5 mm.

[0095] Furthermore, the punch shaft 10 measured between the free shaft end and the radially outermost head underside 34 may have a length h.sub.10 in the range of 1.4 mmh.sub.103 mm, or 1.4 mmh.sub.102.2 mm or 1.4 mmh.sub.101.6 mm. This geometry design in combination with the countersunk head 30 supports a reduced interference contour of the set welding auxiliary joining part 1 and/or a variable applicability in thin components.

[0096] The clamping ring 40 has a height H.sub.40 with respect to the head underside 34 directly adjoining the clamping ring 40 radially outwards in the range of 0.2 mmH.sub.401 mm, such as 0.6 mm and in particular 0.4 mm.

[0097] In FIGS. 5 and 6 further designs of the underside 34 of the element head 30 are shown. In particular, FIGS. 5 and 6 show a sectional enlargement of a part of the element head 30. According to the embodiments of the welding auxiliary joining part 1 described above, the use of only one clamping ring 40 is advantageous. In order to increase the clamping effect of radially inwardly directed material stresses, an outer ring may be arranged at the head underside 34, which surrounds the inner clamping ring 40. In the embodiments of FIGS. 5 and 6, this outer ring also has the configuration of a clamping ring 40. It may also be preferred to design this outer ring as a stamping ring 70, as shown as an example in the embodiments of FIGS. 7 and 8.

[0098] If the outer ring has the configuration of a clamping ring 40, the same geometrical features, functional properties and design principles apply as described above for the clamping ring 40. The clamping ring 40 may be arranged concentrically around the clamping ring 40. In addition, the clamping ring 40 extends continuously around the punch shaft 10 or it is interrupted at regular intervals. According to the embodiment in FIG. 5, the clamping ring 40 arranged radially at the outer side is radially inwardly spaced from the circumferential face 36. As a result, the material displaced by the clamping ring 40 cannot flow off unhindered against the joining direction. Instead, it is blocked by the underside 34 of the element head 30, which causes a further clamping effect and thus fixation of the welding auxiliary joining part in the material of the component A.

[0099] It may also be preferred to arrange the further clamping ring 40 at the radial outer side of the element head 30 as a last point. Accordingly, the radially outer ring side 44 then transitions into the circumferential face 36. This configuration allows an unhindered material displacement radially outwards into the material of the component A surrounding the welding auxiliary joining part 1.

[0100] As can be seen from the embodiments of FIGS. 7 and 8, the outer ring provided in addition to the clamping ring 40 alternatively has the configuration of a stamping ring 70. A stamping ring 70 may be uniformly or axially symmetrically shaped with respect to its cross-section. It follows from this that a material displacement may occur to the same extent radially inwards as radially outwards. During the joining process, the stamping ring 70 is pressed into the component A. The pressed-in stamping ring acts as a seal of the joining position against material or dirt penetrating from the outside, but also against gases occurring, for example, during joining from the inside to the outside. In addition, the adjacent arrangement of the stamping ring 70 and the clamping ring 40 has the advantage that material is compressed between the radially outer ring side 44 and the stamping ring 70. This supports the hold of the welding auxiliary joining part in the component A and the sealing by the stamping ring 70.

[0101] To enhance the effect of the stamping ring 70, it may be arranged radially inwards with respect to the circumferential face 36 at the underside 34 of the element head 30. If unhindered material displacement can be tolerated radially outwards and against the joining direction, it may also be preferred to arrange the stamping ring 70 directly adjacent to the circumferential face 36 (see FIG. 6).

[0102] If it should be necessary to particularly protect the joining position or location against the escape of e.g. gases or against the penetration of contaminants, a stamping ring 70 may be arranged in direct proximity of the punch shaft 10. In this regard, further designs of the welding auxiliary joining part 1 are shown in FIGS. 9 and 10. The stamping ring 70 is positioned within a surrounding clamping ring 40, respectively. For further use of the effect of the clamping ring 40, the clamping ring 40 is configured in such a manner that the material displacement takes place radially inwards against the stamping ring 70. The lateral face of the stamping ring 70, in particular the radially outer lateral face of the stamping ring 70, may take over the function of the lateral face of the stamping shaft 10. Accordingly, the welding auxiliary joining part 1 is then held against the stamping ring 70 by radially inwardly acting mechanical stresses or tensions.

[0103] FIGS. 11 and 12 show further embodiments of the design of the underside 34 of the element head 30. In particular, here, the embodiment of FIG. 5 was combined with the two clamping rings 40, 40 with an additional radially outwardly arranged stamping ring 70. This radially outwardly arranged stamping ring 70 is arranged in the same manner as in the embodiments of FIGS. 7 and 8 radially inwards at a distance from the circumferential face 36 or directly adjacent to the circumferential face 36. The stamping ring 70, which is formed continuously or is regularly interrupted, may ensure a sealing of the joining position to the outside.

[0104] The embodiments of FIGS. 13 and 14 are based on the embodiment of FIG. 7. Here, in order to achieve an additional clamping effect at the stamping ring 70, an additional outer ring was arranged with respect to the existing clamping ring 40 and the stamping ring 70. This outer ring has the shape and configuration of an additional clamping ring 40. Correspondingly, this clamping ring 40 generates a radially inwardly directed additional material flow. This causes additional radial stresses which act against the radial outer side of the stamping ring 70. As in the designs of FIGS. 5 and 6, the radially outer clamping ring 40 is arranged radially inwards at a distance from the circumferential face 36 (see FIG. 13). It may also be preferred that the clamping ring 40 arranged radially at the outer side transitions directly into the circumferential face 36, as can be seen in FIG. 12.

[0105] The embodiments of the underside 32 of the element head 30 shown in FIGS. 16 and 17 show the combination of the embodiment of FIG. 9 with another clamping ring 40 arranged radially at the outer side. This clamping ring 40 arranged radially at the outer side increases the clamping effect which is already achieved by the material displacement due to the clamping ring 40. Thereby the additional clamping ring 40 displaces material radially inwards against the radially outer ring side 44 of the clamping ring 40. The radially outer clamping ring 40 may be arranged radially inwards at a distance from the circumferential face 36, as shown in FIG. 16. It may also be preferred that the clamping ring 40 arranged radially at the outer side is arranged directly adjacent to the circumferential face 36, as can be seen in FIG. 17.

[0106] In the same way as it has been emphasized with regard to the above-described embodiments, the additional clamping ring 40 arranged radially at the outer side has a continuously circumferential shape or it is provided to be interrupted at regular intervals.

[0107] FIGS. 18 and 19 show a combination of the embodiment of FIG. 9 with another stamping ring 70 arranged radially at the outer side. This additional stamping ring 70 arranged radially at the outer side provides an additional and complementary sealing effect to the stamping ring 70 arranged radially at the inner side. In addition, the stamping ring 70 arranged radially at the outer side may be provided to be continuously or to be regularly interrupted. Furthermore, the stamping ring 70 may be arranged radially inwards at a distance from the circumferential face 36, as shown in FIG. 18. According to a further embodiment, which is shown in FIG. 19, the stamping ring 70 arranged radially at the outer side is arranged directly adjacent to the circumferential face 36.