Welding auxiliary joining part, matrixes for placing the welding auxiliary joining part, and connection and production methods for the welding auxiliary joining part and the matrixes

Abstract

The disclosure is related to various connecting methods for a welding auxiliary joining part having a head and a rounded tip for setting in at least one first component having a die as counter-bearing, which has a concave recess with an inner wall having at least in sub-areas an arc shape and having a matrix radius MR in the range from 1.0 mmMR60 mm, for preparing a subsequent welding method. The geometry of the welding auxiliary joining part and the die meet the following condition: $0.001\frac{\mathrm{SR}}{\mathrm{MR}}0.1,$
in particular $0.002\frac{\mathrm{SR}}{\mathrm{MR}}0.08,$
wherein SR designates a tip radius of the rounded tip of the welding auxiliary joining part.

Claims

1. A connection method for a welding auxiliary joining part with a head and a rounded tip for setting in at least one first component of a poorly weldable material with a die as a counter-bearing having a concave recess with a cone-shaped inner wall in at least a partial portion with a die radius MR in a range of 1.0 mmMR60 mm for preparing a subsequent welding method with the connection method comprising the steps of: setting the welding auxiliary joining part in the at least one first component of the poorly weldable material and against the die, wherein there is a material displacement gap provided between a tip portion of the welding auxiliary joining part and the die geometry into which the poorly weldable material of the at least one first component is capable of being removed radially outwardly, and deforming the tip portion of the welding auxiliary joining part directly at the die, while the following conditions are fulfilled: $0.001\frac{\mathrm{SR}}{\mathrm{MR}}0.1,$ wherein SR denotes a tip radius of the rounded tip of the welding auxiliary joining part.

2. The connection method according to claim 1, wherein the tip radius SR and the die radius MR show the following ratio: MR2.Math.SR.

3. The connection method according to claim 1, wherein the die radius MR is selected from the range 20 mmMR40 mm and the tip radius SR is selected from the range 0.1 mmSR1.5 mm.

4. The connection method according to claim 1, wherein the welding auxiliary joining part has a cone-shaped portion, which is positioned between the rounded tip and the head, which widens towards the head and which comprises a tip angle SW between a center axis of the cone-shaped portion and a lateral cone surface in the range of 35SW80.

5. The connection method according to claim 1, in which the welding auxiliary joining part is accelerated while setting to a speed in the range of 1 m/sv40 m/s, and/or comprising the further step of: welding the first component having the welding auxiliary joining part to a second component made of weldable material.

6. A connection method for a welding auxiliary joining part with a head and a rounded tip for setting in at least one first component of a poorly weldable material with a die as a counter-bearing having a concave recess with an arc-shaped inner wall at least in a partial portion thereof, wherein said die has a die radius MR in a range of 1.0 mmMR60 mm for preparing a subsequent welding method, wherein the connection method comprises the steps of: setting the welding auxiliary joining part in the at least one first component of the poorly weldable material and against the die, wherein there is a material displacement gap provided between a tip portion of the welding auxiliary joining part and the die into which the poorly weldable material of the at least one first component is capable of being removed radially outwardly, and deforming the tip portion of the welding auxiliary joining part directly at the die, while the following conditions are fulfilled: $0.01\frac{\mathrm{SR}}{\mathrm{MR}}1,$ wherein SR denotes a tip radius of the rounded tip of the welding auxiliary joining part.

7. The connection method according to claim 6, wherein the die has a concave recess with the die radius MR in the range of 1.5 mmMR5 mm, wherein the arc-shaped recess having an at least partial arc-shaped inner wall opens in a circumferential convex region, in particular with an outer die radius in the range of 15 mmMR.sub.a40 mm.

8. The connection method according to claim 6, wherein the tip radius SR and the die radius MR show the following ratio: MR2.Math.SR.

9. The connection method according to claim 6, wherein the die radius MR comprises the range of 1.5 mmMR5 mm and the tip radius SR comprises the range of 0.1 mmSR1.5 mm.

10. The connection method according to claim 6, wherein the welding auxiliary joining part has a cone-shaped portion which is positioned between the rounded tip and the head, which opens towards the head and which comprises a tip angle SW between a center axis of the cone-shaped portion and a lateral conical surface in the range of 35SW80.

11. The connection method according to claim 6, in which the welding auxiliary joining part is accelerated while setting to a speed in the range of 1 m/sv40 m/s, and/or comprising the further step of: welding the first component having the welding auxiliary joining part to a second component made of weldable material.

12. A connection method for a welding auxiliary joining part with a head and a rounded tip for setting in at least one first component of a poorly weldable material with a die as a counter-bearing comprising a concave recess with an inner wall arc-shaped in at least a partial portion with a die radius MR in a range of 1.0 mmMR60 mm, for preparing a subsequent welding method, wherein the connection method comprises the steps of: setting the welding auxiliary joining part in the at least one first component of the poorly weldable material and against the die, wherein there is a material displacement gap provided between a tip portion of the welding auxiliary joining part and the die into which the poorly weldable material of the at least one first component is capable of being removed radially outwardly, and deforming the tip portion of the welding auxiliary joining part directly at the die, while the following conditions are fulfilled: $0.01\frac{\mathrm{SR}}{\mathrm{MR}}0.5,$ wherein SR denotes a tip radius of the rounded tip of the welding auxiliary joining part.

13. The connection method according to claim 12, wherein the tip radius SR and the die radius MR show the following ratio: MR2.Math.SR.

14. The connection method according to claim 12 wherein the die radius MR comprises the range of 20 mmMR40 mm and the tip radius SR comprises the range of 1 mmSR1.5 mm.

15. The connection method according to claim 12, in which the welding auxiliary joining part is accelerated while setting to a speed in the range of 1 m/sv40 m/s, and/or comprising the further step of: welding the first component having the welding auxiliary joining part to a second component made of weldable material.

16. A connection method for a welding auxiliary joining part with a head and a tip for setting in at least a first component of a poorly weldable material with a die as a counter-bearing, which has a recess with a die angle MW between a central axis of the recess and an inner wall of the recess, for preparing a subsequent welding method, the connection method comprising the steps of: setting the welding auxiliary joining part in the at least one first component of the poorly weldable material and against the die, wherein there is a material displacement gap provided between the welding auxiliary joining part and the die into which the poorly weldable material of the at least one first component is capable of being removed radially outwardly, and deforming the tip portion of the welding auxiliary joining part at the die, while the following conditions are fulfilled: $0.4\frac{\mathrm{SR}}{\mathrm{MR}}1.0,$ wherein SW denotes a tip radius of the tip of the welding auxiliary joining part measured between the central axis and a outer surface of the welding auxiliary joining part.

17. The connection method according to claim 16, wherein the die has an angled recess with the die angle MW in the range of 70MW90.

18. The connection method according to claim 16, wherein the tip angle SW and the die angle MW show the following ratio: MWSW10.

19. The connection method according to claim 16, wherein the tip angle SW comprises a range of 35SW80.

20. The connection method according to claim 16, wherein the welding auxiliary joining part has a conical region, which is positioned between the tip and the head and which expands towards the head, and the conical portion having the tip angle SW between the central axis and a lateral conical surface.

21. The connection method according to claim 16, in which the welding auxiliary joining part is accelerated while setting to a speed in the range of 1 m/sv40 m/s, and/or comprising the further step of: welding the first component having the welding auxiliary joining part to a second component made of weldable material.

Description

4. DETAILED DESCRIPTION OF THE DRAWINGS

(1) The present disclosure is explained in more detail with reference to the accompanying drawings. There are shown:

(2) FIG. 1 the basic structure of the here-shown connection method, consisting of the setting method and welding according to DE 10 2012 010 870 from the prior art,

(3) FIG. 2 is a schematic side view and a partially sectional view of an embodiment of the inventive welding auxiliary joining part,

(4) FIG. 3 is a side perspective view and a sectional view of a die,

(5) FIG. 4 is a schematic vertical section through an embodiment of a die in parallel to the central axis of the die,

(6) FIG. 5 shows a first preferred combination of geometries of the welding auxiliary joining part and the die for the setting process,

(7) FIG. 6 is a further combination of a geometry of the welding auxiliary joining part with a geometry of the die for the setting process of the welding auxiliary joining part,

(8) FIG. 7 shows a further combination of a geometry of the welding auxiliary joining part with an adapted geometry because the template for the setting method, and

(9) FIG. 8 shows another combination of the geometry of the welding auxiliary joining part with an adapted geometry because the die for the setting process of the welding auxiliary joining part.

5. DETAILED DESCRIPTION

(10) The present disclosure serves for connecting at least one first component 20, 22 made of a non- or poorly-weldable material, further referred to as poorly-weldable material, with at least one second component 30 made of a weldable material by welding. To this purpose, a welding auxiliary joining part 10 consisting of weldable material is initially set at least into the at least one first component 20, 22. After the setting procedure of the welding auxiliary joining part 10 has been completed, the first component 20 is welded to the second component 30 by means of the set welding auxiliary joining part 10. Thereby, a welded connection between the welding auxiliary joining part 10 and the second component 30 is produced. A method like this has been described in DE 10 2012 010 870, that is referred to for supplementary technical information.

(11) As an example, FIG. 1 shows FIG. 16 from DE 10 2012 010 870. Therein, the welding auxiliary joining part 10 is first set into both of the first two components 20, 22 made of a poorly-weldable material. A die 50, which will be discussed in greater detail below, acts as a counter-bearing/abutment for the setting procedure of the welding auxiliary joining part 10. The welding auxiliary joining part 10 is formed as a nail. The shape of the welding auxiliary joining part 10 is also explained below in greater detail.

(12) During the substeps a, b, c and d according to FIG. 1, the welding auxiliary joining part 10 is first set substantially rotation-free into the not pre-punched first components 20, 22 by means of a punch (not shown) with a force F. Thereby, a material displacement takes place in the first components 20, 22 by means of the welding auxiliary joining part 10 without component material being punched out during the setting procedure. In depiction d, it can be seen that the welding auxiliary joining part 10 is deformed at the die 50. The deformation in the area of the tip of the welding auxiliary joining part forms a welding head 70, a welding projection or generally a suitable welding contact area to be welded to the second component 30 in accordance with depiction e. The welding takes place by means of known electric welding procedures, for example resistance welding, whereby the welding electrodes 64, 66 are in contact with the second component 30 and the welding auxiliary joining part 10. For that reason, an electric welding current is flowing between the welding electrodes 64, 66 producing a welding spot 60 and, after cooling, a welded connection at the interface between the welding auxiliary joining part 10 and the second component 30. The size, shape, speed as well as the type of the forming of the welding spot 60 is, among others, dependent on the welding contact area of the welding auxiliary joining part 10, which has been deformed during setting, to the second component 30. A suitable production and configuration of the welding contact area is carried out by the deformation of the welding auxiliary joining part 10 at the die 50, wherein the shape of a tip portion 13 of the welding auxiliary joining part 10 is matched to a shape of the die 50 in the impact region of the welding auxiliary joining part 10 during setting.

(13) The materials of the components to be connected 20 and 30 are not mutually compatible for welding, so that they are welded indirectly via the welding auxiliary joining part 10. The weldable materials include steel and high-tensile steels such as 22MnB5 (CEV=0.5), B27 (CEV=0.54), 32MnCrB6 (CEV=0.6), of which, for example, framework structures in vehicle manufacturing are produced. Non- or poorly-weldable materials include materials that can only be poorly or not at all welded to other components without constructive aids. This also includes weldable materials, which, however, have in their material combination no or only a small welding compatibility to the material of a component to be connected to. This means that the generally weldable materials cannot be welded to each other or only in a difficult or poor way. These materials include, for example, plastics, fiber-reinforced plastics, aluminum, cast iron or other iron alloys as well as steels, such as spring steels with a CEV>0.8.

(14) The setting of the welding auxiliary joining part 10 is carried out by the above-mentioned punch, which is moved by a hydraulic, electromagnetic, electric, pneumatic or gas-powered drive. According to a further embodiment, the welding auxiliary joining part is, depending on the joining task, driven in by means of a pulse-like force which accelerates the welding auxiliary joining part 10 up to a speed in the range of 1 m/s to 40 m/s, preferably 1 m/s up to and including 5 m/s, further preferred in the range of 10 m/sv40 m/s, even more preferred in the range of 20 m/sv40 m/s, and also preferred to at least 30 m/s. Such a driving in or setting process has been described in DE 10 2006 002 238, that is referred to at this point. After the setting process has been completed, the at least one component 20, 22 of non- or poorly-weldable material is provided with the welding auxiliary joining part 10, which provides the evenly or protrudingly arranged welding contact area, hereafter called welding head. Additionally, a head 12 of the welding auxiliary joining part protrudes from the component 20, 22 or abuts it. Since the at least one first component 20, 22 and the welding auxiliary joining part 10 are reliably connected to each other, it is preferred to transport this combination and to weld it elsewhere. In this way, the subsequent welding can follow the setting at the same place.

(15) As it has been already mentioned above, the formation of the welding head 70 is inventively achieved by a selective matching of the shape of the welding auxiliary joining part 10, in particular the shape of a tip portion 12, to a shape of the die 50. A further embodiment of the welding auxiliary joining part 10 is shown in FIG. 2. FIG. 3 shows a side and a sectional view of a preferred die 50. FIG. 4 schematically shows a further preferred geometric design of the die 50, along with the parameters to describe it. FIGS. 5 to 8 depict preferred shaping configurations of the welding auxiliary joining part 10 and the die 50 which have been matched to each other.

(16) FIG. 2 shows a partial sectional view of the preferred welding auxiliary joining part 10 with the tip portion 12, a shank 14 and a head 16. It is generally required that the welding auxiliary joining part 10 is adapted to the joining task and particularly to the material properties of the at least one first component 20. In particular, the welding auxiliary joining part 10 must be harder than the at least one first component 20. In this way it is ensured that a deformation of the welding auxiliary joining part 10 takes place only after the at least one first component 20 has been penetrated. Additionally, it is avoided that the welding auxiliary joining part 10 already expands laterally when penetrating the first component 20. Furthermore, the preferred welding auxiliary joining part 10 comprises a sufficiently high residual ductility to plastically deform without cracks when hitting the die 50. In addition, it has been recognized that, when the strength of the welding auxiliary joining part 10 increases, a higher driving force of the welding auxiliary joining part 10 is required. Thus, the strength of the welding auxiliary joining part has to be in the range of 800 to 1200 N/mm.sup.2 when, for example, thin aluminum sheets of 0.8 to 2.5 mm are used. The strengths vary within this range depending on the geometry of the tip of the welding auxiliary joining part 10. In accordance with the material of the welding auxiliary joining part 10, the material of the die 50 is selected from harder ones in order to ensure the deformation of the welding auxiliary joining part 10.

(17) Referring to the illustration of the welding auxiliary joining part 10 in FIG. 2, the head 16 preferably has a diameter of 5 to 12 mm, more preferably 7 to 10 mm, and further preferred of 8 mm. Depending on the joining task to be solved and the stability required for the later connection of the welding auxiliary joining part 10, the height of the head 16 varies in the range of 0.8 to 2 mm, preferably of 1.0 to 1.8 mm. According to a further embodiment, the head is formed planar on its upper side, i.e. opposite to the joining direction S. In this way, a sufficiently large contact area is provided for the driver piston. It is further preferred to equip the head 16 laterally with a cylindrical or a rounded circumferential surface.

(18) Further, the head 16 includes an under-head radial groove 17. This under-head radial groove 17 serves for receiving the material displaced from the at least one first component 20. The material received in the under-head radial groove 17 preferably has, at a shear stress situation, a stabilizing impact on the welding auxiliary joining part 10 already set into the component 20. The under-head radial groove 17 preferably has a height of 0.2 to 0.6 mm and a width of 1.5 to 2.0 mm. In addition, the under-head radial groove preferably runs radially upwardly so that an outer, planar annular surface is formed at the bottom side of the head 16. This annular surface leans on the first component 20 and, by a sufficiently radial width, it avoids a notch effect of the bottom side of the head in the first component 20. Additionally, and preferably after the setting procedure has been completed, the bottom side of the head closes the area of the under-head radial groove anticorrosively, preferably hermetically and without a gap between the bottom side of the head and the component by abutting on the component.

(19) The shank 14 is an optional element of the welding auxiliary joining part. It establishes a connection between the head and the tip portion 12. It is also preferred to directly join the tip portion 12, which preferably is provided with a sharp tip (see FIG. 5), a dome-shaped round tip (see FIG. 6) or a rounded tip (see FIGS. 7 and 8) to the head 16. During the setting process, the shank 14 stabilizes the welding auxiliary joining part 10 when penetrating the first component 20. In addition, the shank is compressed at the die along with the tip portion 12, whereby it expands radially. As the diameter of the shank 14 at the transition between the shank 14 and tip portion 12 is, after compression, larger than the shank diameter at the transition between the shank 14 and the head 16, it forms an undercut which supports the holding of the welding auxiliary joining part within the first component 10. Preferably, the shank has a diameter of 3 to 4 mm. The length of the shank 14 varies in the range of 0 mm<l.sub.s15 mm, preferably at least 1 mm and further preferred 1 mml.sub.s6 mm, depending on the thickness of the components 20, 22 to be joined.

(20) The tip portion 12 of the welding auxiliary joining part 10 consists of a tip 11 and an adjoining cone-shaped portion 13. The tip portion 12 has an influence on the displacing of material during penetration of the welding auxiliary joining part 10 into the first component 20. It is preferred to form the tip portion 12 by the above-mentioned tip 11 and the cone-shaped portion 13. This tip 11 is preferably formed sharp or has a rounded shape. According to a further embodiment, the tip portion 12 has a dome shape. In this case, the shank closes with an arc shape in the joining direction, wherein the diameter of the circular arc covers the entire diameter of the shank 14.

(21) The different shapes of the tip portion 12 are illustrated in FIGS. 5 to 8. FIG. 5 shows a sharp tip 11 merging into the cone-shaped portion 13. The sharp tip 11 is characterized by a tip angle SW, which is located between the central axis M and the radial outer circumferential surface of the tip 11 and the cone-shaped portion 13. Therefore, the tip angle SW also describes the shape of the cone-shaped portion 13.

(22) In FIG. 6, the tip portion 12 or the cone-shaped portion 13 are configured with a rounded shape. The rounded tip 11 extends over the entire diameter of the shank 14, similar to a dome. It is also preferred to omit the shank 14 so that the tip portion 12 merges directly into the head 16. The rounded tip 11 of FIG. 6 is described by a tip radius SR. The circular arc comprising the tip radius SR, which forms the rounded dome-shaped tip 11, has its center on the central axis M.

(23) In FIGS. 7 and 8, the tip portion 12 is a combination of the rounded tip 11 and the cone-shaped portion merging into the optional shank 14.

(24) According to a further embodiment of the cone-shaped portion 13, the circumferential surface is formed planar or curvilinear. The bending of the circumferential surface is convex or concave in order to influence the material displacement behavior while penetrating into the first component 20. It is also preferred to equip the cone-shaped portion 13 with a triangular, rectangular or polyhedral base instead of a round base (not shown).

(25) The dies 50 acting as counter-bearings/abutments are formed in adaptation with the preferred welding auxiliary joining parts 10 of FIGS. 5 to 8. The contour of the die has an influence on the formation of the connection between the welding auxiliary joining part 10 and the at least one first component 20. In this regard, it should be noted that the undercut in the shank portion of the welding auxiliary joining part 10 increases with the flattening of the die-contour, i.e. with a decreasing depth of the recess 52 of the die 50. At the same time, the required joining energy increases in order to realize an abutting of the head 16 of the welding auxiliary joining part 10 on the first component 20. With an increasing of the depth of the die-contour of the die 52, the weldability of the welding auxiliary joining part 10, which has been reshaped in the recess 52, increases. Furthermore, a deeper die-contour 52 contributes to a better reproducibility of the formation of the welding spot 60. However, a deeper die-contour has the disadvantage that the welding auxiliary joining part 10 must be correspondingly formed longer.

(26) With respect to the die-contour, i.e. the shape of the recess 52, it has been proven that the selective deep landing of the recess 52 leads to a higher energy-bundling during the subsequent welding. In this way, a more effective initial welding ignition is possible. It is further preferred to provide a minimum of contour radii 56 in the recess 52 in the die 50. By reducing the contour radii, a uniform flow of the displaced joining material is supported. In this way, it is avoided that displaced material jams on the welding head 70. In addition, it is preferably advantageous to select the inner radius of the die as large as possible. Since such a condition results in a decreased slope of the recess 52 of the die 50, a displacement of material is possible with a lower energy consumption.

(27) The die 50 comprises a concave recess 52. The concave recess 52 is constructed in different ways, according to various embodiments of the present invention. According to a first embodiment, the concave recess 52 is formed arc-shaped, as can be seen in FIGS. 6 to 8. A die radius MR.sub.1, MR.sub.2, MR.sub.3, which has its origin on the central axis M of the concave recess 52, defines the preferably continuous, or at least partially continuous arc shape of the concave recess.

(28) According to another embodiment (see FIG. 4), the concave recess 52 comprises, at least in a partial area 55, an arc-shaped, radial inner side 54 or inner wall. The partial areas 55 are also defined by the respective section of the die radius MR, which will be mentioned below, in particular by the die radius MR.sub.55 of the partial areas 55. The die radius MR.sub.55 of the partial areas 55 preferably has its origin in a point on the central axis M or on a straight line G running parallel to the central axis M. Preferably, in a vertical sectional view of the concave recess 52 according to FIG. 4, the concave recess 52 comprises two arc-shaped sectional areas 55, which have been arranged oppositely to each other and which have the radius MR.sub.55 or MR.sub.55. According to a non-illustrated spatial view of the die 50 along with the concave recess 52, the straight lines G are lying on a cylindrical surface, which is arranged concentrically around the central axis M.

(29) In FIG. 4, the partial areas 55 are preferably connected to each other by different shapes of the die base 58 which are designable according to the joining task. According to different embodiments, the die base 58 is flat, corrugated, angled, curved or has another shape. It is further preferred to form concentric landings in the radial inner side 54 of the concave recess 52, which, for example, can be perceived as contour radii 56.

(30) In the following, the dies 50 and connection methods are described using the example of a completely or partially continuous arc-shaped concave recess 52, by means of which the at least one first component 22 is connected to the second component 30 via the welding auxiliary joining part 10. In the same way, a die 50 is usable at this point, whose concave recess 52 has arc-shaped partial areas 55 in the vertical sectional view of the die 50. In a first step I, the welding auxiliary joining part 10 is set into the at least one first component 20. Due to the shapes of the tip portion 12 of the welding auxiliary joining part 10 and of the die 50, which have been preferably adapted to each other, a deformation of the welding auxiliary joining part 10 in the welding head 70 takes place (step II). Subsequently, the welding head 70 is welded to the second component 30 (step III).

(31) It has been proven advantageous and economical to produce the welding auxiliary joining part 10 by a cold forming process with the geometric shapes discussed in greater detail below. The used dies 50 (see below) are also formed (step H.sub.m1) and finished (step H.sub.m2) according to known methods in the geometries discussed below.

(32) The embodiment according to FIG. 4 shows the cone-shaped portion 13 comprising a non-rounded tip 11 which is tapered sharply or pointed. The tip portion 13 includes a tip angle SW.sub.1 in the range of 35SW.sub.180, preferably 45SW.sub.170.

(33) It is preferable that the geometries of the welding auxiliary joining part 10 and the die 50 fulfill the following condition. This is because, in this case, both the setting process of the welding auxiliary joining part in the first component 20 and the formation of a welding head 70 suitable for the subsequent welding is supported. These preferred geometry conditions of the welding auxiliary joining part 10 and the die 50 can be defined as follows with reference to the tip angle SW.sub.1 and the die angle MW:

(34) $0.4\frac{{\mathrm{SW}}_1}{\mathrm{MW}}1,$
in particular

(35) $0.6\frac{\mathrm{SW}}{{\mathrm{MW}}_1}0.8,$

(36) This welding auxiliary joining part 10 with a non-rounded tip 11 is set by means of a die 50 as counter-bearing/abutment which comprises an angled recess 52 in the setting direction S. The recess 52 is formed cone-shaped with a die angle MW between the central axis M and a radial inner side 54 of the recess 52. The die angle MW.sub.1 is selected from the range of 70MW.sub.190.

(37) It is preferred that the tip geometry and the die geometry, which are arranged oppositely to each other during setting, form a material displacement gap between them, through which the material of the at least one first component 20 can be removed radially outwardly. It is understandable that the size of the gap can only be assessed at the time at which the welding auxiliary joining part meets the die, i.e. before the tip portion 12 of the welding auxiliary joining part 10 is deformed at the die 50, as due to the deformation of the welding auxiliary joining part 10 at the die 50, this material displacement gap is exposed to constant change. Such a material displacement gap is formed as long as the difference of the die angle MW and the tip angle SW.sub.1 of the welding auxiliary joining part 10 preferably fulfils the following condition: MWSW.sub.110.

(38) If, preferably, the ratio ranges mentioned above are combined with one or more of the above-mentioned geometric conditions and if the selected conditions are cumulatively fulfilled, further embodiments of the present disclosure arise.

(39) According to a further embodiment shown in FIG. 6, the tip radius SR.sub.1 of the dome-shaped welding auxiliary joining part 10 and the die radius MR.sub.1 of the concave, preferably arc-shaped, recess 52 of the die 50 fulfill the following proportion:

(40) $0.01\frac{{\mathrm{SR}}_1}{{\mathrm{MR}}_1}0.5,$
in particular

(41) $0.03\frac{{\mathrm{SR}}_1}{{\mathrm{MR}}_1}0.3$
wherein the die radius MR.sub.1 is preferably selected from the range of 1 mmMR.sub.160 mm. Also in this embodiment, the preferred circular arcs of the tip 11 of the welding auxiliary joining part 10 and of the concave, preferably arc-shaped, recess 52 of the die 50 are matched to each other in such a way that an advantageous material displacement gap is formed between them even before the deformation of the welding auxiliary joining part 10 at the die 50. The formation of the material displacement gap is preferably supported if the die radius MR.sub.1 reaches or exceeds twice the value of the tip radius SR.sub.1, i.e. MR.sub.12.Math.SR.sub.1.

(42) According to a further embodiment, the setting result of the welding auxiliary joining part and the shape of the welding head 70 could be further improved. To this end, the die radius MR.sub.1 was selected from the range 20 mmMR.sub.140 mm and the tip radius SR.sub.1 was selected from the range 1 mmSR.sub.11.5 mm.

(43) Another connection method is illustrated with reference to FIG. 7. Before welding, the illustrated preferred welding auxiliary joining part 10 is at first set against the also preferred die shape. The welding auxiliary joining part 10 includes the non-illustrated head 16, the optional shank 14, the cone-shaped tip portion 12 with the tip angle SW.sub.2 as well as a rounded tip 11. The rounded tip 11 is defined by the tip radius SR.sub.2 wherein the center of the circular arc of the tip 11 is located on the central axis M.

(44) The concave, preferably arc-shaped, recess 52 of the die 50 is at its lowest point defined by the die radius MR.sub.2. Again, the center of the circular arc is located on the central axis M.

(45) When setting the welding auxiliary joining part 10 into the at least one first component 20 and against the die 50 shown in FIG. 7, the material displacement gap, which has been also described above, is formed when the following condition is fulfilled:

(46) $0.01\frac{{\mathrm{SR}}_2}{{\mathrm{MR}}_1}1,$
in particular

(47) $0.1\frac{{\mathrm{SR}}_2}{{\mathrm{MR}}_1}0.6.$
In this context, it is particularly preferred that the concave, preferably arc-shaped, recess 52 of the die 50 comprises the die radius MR in the range of 1.5 mmMR5 mm. Furthermore, it can be seen from the preferred embodiment illustrated in FIG. 7 that the concave, preferably arc-shaped, recess 52 of the die 50 opens into a circumferential, convex-shaped portion against the setting direction S. In particular, this circumferential convex portion is defined by an outer die radius MR.sub.a in the range of 15 mmMR.sub.a40 mm.

(48) The die shape used preferably herein generates a welding projection which strongly tapers in the joining direction and which comprises a small contact area in the setting direction S. This shape of the welding projection has the advantage that it facilitates the welding initiation, especially with respect to light arc welding and projection welding.

(49) With respect to the material displacement gap also used in this inventive embodiment, it is preferable that the tip radius SR.sub.2 and the die radius MR fulfill the following condition: MR.sub.22.Math.SR.sub.2. In this context, it is further preferred that the tip radius SR.sub.2 is in the range of 0.1 mmSR.sub.21.5 mm. It is particularly preferred that the tip radius SR.sub.2 in the range of 0.8 mmSR.sub.21.2 mm is combined with a tip angle SW.sub.2 in the range of 35SW.sub.280, preferably 45SW.sub.270 and in particular SW.sub.2=55.

(50) FIG. 8 illustrates another alternative connection method in which the welding auxiliary joining part 10 according to FIG. 7 is set against a concave, preferably arc-shaped, die 50 with a die radius MR.sub.3 of 1.0 mmMR.sub.360 mm. The subsequent welding is supported if during the setting process the following geometric specifications are fulfilled with respect to the welding auxiliary joining part 10 and the die recess 52:

(51) $0.001\frac{{\mathrm{SR}}_3}{{\mathrm{MR}}_3}0.1,$
in particular

(52) $0.002\frac{{\mathrm{SR}}_3}{{\mathrm{MR}}_3}0.08.$

(53) Preferably, the suitable material displacement and formation of a desired welding head 70 is supported when setting the welding auxiliary joining part 10 by the fact that the tip radius SR.sub.3 and the die radius MR.sub.3 meet the following ratio: MR.sub.32 SR.sub.3. In this context, preferably the die radius MR.sub.3 is selected from the range 20 mmMR.sub.340 mm and the tip radius SR.sub.3 is selected from the range 0.1SR.sub.31.5 mm.

(54) In a further embodiment of the method described herein, the welding auxiliary joining part 10 comprises a cone-shaped portion 12 arranged between the rounded tip 11 and the head 16 of the welding auxiliary joining part. This cone-shaped portion 12 is characterized by a tip angle SW.sub.3 in the range of 35SW80.

(55) Since the die 50 according to FIG. 8 preferably has a larger die radius MR than the die with convex end according to FIG. 7, a larger contact area on the deformed welding auxiliary joining part 10 results for the subsequent electrical welding to the second component 30. In this context it is particularly preferred if the following conditions are met: 0.8 mmSR.sub.3<1.2 mm, SW=55 and MR.sub.3=30 mm.

(56) It is also preferred to equip the die 50 according to the above-described alternatives with a recess 52 similarly deep but formed elliptically.

(57) Certain embodiments or components or features of components have been noted herein as being preferred and such indications are to be understood as relating to a preference of the applicant at the time this application was filed. Such embodiments, components or features noted as being preferred are not required for implementation of the inventions disclosed herein unless otherwise indicated as being required, or unless specifically included within the claims that follow.