DE8330886U1 - Contact stud - Google Patents

Description

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Fine metal Company with limited liability

7033 Herrenberg

"

Contact stud

The invention relates to a contact bolt for a contact member of a Kontaktiervörrichtun <tj according to the Ofoer- concept of claim 1.

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Contacting devices of this type are known (e.g. KRÜGER "Test equipment for the electrical testing of printed circuit boards for clocks", Yearbook of the German Society schaft für Chronometrie, Volume 30, 1979, pp. 269-276). Such contacting devices are used for testing from circuit boards or other electronic components in the electronics industry to newly manufactured circuit boards or the like before or after they have been fitted to ensure that they are free of errors and to be able to easily check or measure by the test object on several or in general mostly

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g very many places at the same time through contact bolts the contacting device is scanned electrically. The test centers are often very close to one another / and the closer, the narrower the conductor and the smaller the conductor spacing of the test object. and Although such Xontaktiervorriehtungen mainly serve to make the conductor tracks even more unpopulated Printed circuit boards for short circuits between adjacent conductor tracks or other faults in the conductor tracks, For example, interruptions or the like, to be checked before they are equipped with further electronic components will. In many cases, such contacting devices can also be used not only for the test purposes described above, but also for measuring purposes, possibly for measuring purposes of already equipped lines.

_2Ö terplatten or other electronic components, e.g. for resistance measurements and the like.

The contact pins of the contact members of the contacting device are normally borrowed as a whole in an axially moving manner and axially spring-loaded, for example. They can be stored in a straight line in sleeves such as pistons and loaded by compression springs. Such contact members are also referred to as spring contact pins. It is also possible for the contact bolts not in sleeves mono- ₃ Q zein virtually lead, but for example, in wells of a common support plate or the like to lead. And to charge it by its own weight oder.durch to another plate supported compression springs axially. It is also conceivable to design the contact pin so that it can spring axially in itself,

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by using an area of it as a curved spiral spring, For example, as a U-shaped spring clip or the like. It is also possible to attach the contact pin to a separate one To arrange spiral spring firmly.

In the case of the known contact bolts of this type, the procedure _{so far 3 was} that a blind hole was provided in the contact head, | into which the shaft was positively inserted and it. ■ | was at two diametrically opposite ■ <

Place the contact head one after the other

so-called upper lap welding is carried out using focused laser beams. The laser beam of a so-called welding laser was focused on the welding point by means of an optical system in order for the welding beam "

the greatest possible energy density and the greatest possible depth; the melting of the material, d. h, who is at Welding to achieve forming welds. Any such Overlap weld resulted in a weld point, its largest diameter at most 1.2 times its depth corresponded. Such welds were previously only used

Contact studs were made, the shafts of which had a maximum diameter of 1.2 mm at the welding points before welding. The focused laser beams caused welding points, which reached approximately to the longitudinal center axis of the shaft ^: or even beyond it, so that the

two mutually diametrical welding points normally met or at best had only very small tolerance-related distances from each other, which did not occur deliberately, but rather tolerance-related.

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This welding of the contact head to the shaft was used to establish a firm mechanical connection between these two Parts to reach. However, these known welds described with laser beams focused on the weld points are not always satisfactory. So satisfied mechanical strength of the weld joint often not and the electrical resistance of the contact bolt was in difficult to control in series production. Since the contact pin conducts the test or measurement current when testing or measuring a point of the respective test object contacted by it, it is desirable, however, that its electrical resistance in series production

better manageable 1st.

It is therefore an object of the invention to produce a contact bolt of the type mentioned, whose electrical resistance in series production can be better controlled, with better mechanical Strength of the connection between the contact head and shaft should be achievable.

This object is achieved according to the invention by a contact bolt according to claim 1.

The contact bolt can have one or more welding points.

By the measure according to the invention, which for Kontaktbol » zen is provided, the shafts of which have a diameter of at the intended welding points before welding have a maximum of 3 rom, preferably from about p, 4 to 2 mm, the welding points penetrate less deeply

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than before in the shafts, which the electrical properties of the contact bolt can handle better and also higher Can achieve mechanical strength, and that is in the cross-sectional area of the shaft on which a Schjs? Point is present, more through the welding

jQ unaffected material than with deeper penetration of the welding point in the shaft, which has a positive effect on the electrical properties and strength of the contact bolt. This low penetration depth reduces the scattering of this electrical resistance

jK Status of the contact pin in its series production of .Kontaktbolzen to contact pins, which iat an advantage in contacting devices of the present type. Particularly low electrical resistances of the Kcr'caktbolzens can also be achieved with given materials. When the spot weld is made by lap welding

2Q, that is to say is an overlap weld point, can preferably it should be provided that the largest diameter of the welding point is at least 1.5 times its depth, is preferably about 2 to 4 times its depth in the contact pin. This is particularly high

2g strength of the welded joint reached and the scatter the electrical resistance of the contact bolt, which is largely determined by the welding point (s), even smaller in series production.

If multiple spot welds are provided, it is for that Strength of the contact bolt as well as its electrical resistance is particularly favorable when the weld points or at least two welding points are arranged offset from one another in the axial direction of the contact bolt

«Ρ, where the offset is preferably at least 0.2 mm,

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can particularly advantageously be at least 0.4 mm. In general, two welding points are necessary in the extreme case and by axially displacing them in the longitudinal direction of the contact bolt, the distance between them in the shaft increases and the IQ strength of the control bolt is less affected by the welding points. This axial offset can also have a favorable effect on an even smaller spread of the electrical resistance in series production.

In view of the small contact pin diameter on the

Welding point that penetrates the shaft only relatively slightly ^ as the invention provides, the The energy density of the welding beam causing the weld should be considered to be sufficiently low. In which the The welding beam performing the welding may preferably be a laser beam, but it does come an electron beam or possibly also a microplasma beam is also possible. It can therefore be preferred Laser welding may be provided. Electron beam welding can also be used. Also micro plasma welding it is an option. The latter, however, is more difficult to carry out, since here tight tolerances have to be adhered to in contrast to laser beam welding and electron welding

3Q beam welding is difficult.

In particular, welding can be done with defocused Welding beams take place, the energy density of which is reduced at the welding point due to the defocusing, 3g so red spot weld as intended, only relatively little penetrates the shaft. The penetration depth of the welding point in the shaft is max. D / 3, at most

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but 0.35 mm, preferably 0.1 to 0.2 mm. The scattering is due to the latter low penetration depth of electrical resistance especially small and they

β is also particularly favorable for high mechanical strength of the welded joint.

The visual welding is possible both in the form of an overlap weld and in the form of a corner or fillet weld. The weld point produced by a lap weld is referred to as a lap weld point and the weld point produced by a corner or fillet weld is referred to as a corner or fillet weld.

The welding point can preferably be produced in such a way that its maximum diameter, measured in the direction the longitudinal axis of the contact head, is greater than half the outer diameter of the contact head at the welding point. This gives the spot weld a diameter as large as it would for a particularly low scatter the electrical resistance of the contact bolt and high mechanical strength of the connection between Contact head and shaft is particularly favorable.

2g One can provide that the contact head in the simplest Case is connected to the shaft by means of a single spot weld. However, it is also possible and in many cases it is expedient to provide a plurality of welding points. In the latter case you can

₃ Q the welding points can in many cases be conveniently arranged to form a so-called spot weld. Under a point seam is an arrangement of at least three

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g spot welds in a None understood next to each other. The visual weld points of a spot seam can, for example, also be distributed around the shaft, that is to say, for example, around its circumference, three weld points _{can be arranged at preferably equally large central angular center distances 1Q} from one another.

The materials / from which the contact head and shaft are made / can be identical to or different from "For combing the head or shaft preferably steel, special expedient _1S standard carbon steel (carbon steel) or CrNi steel (stainless steel) / cube (copper-beryllium , also called beryllium bronze, preferably with 1.7% or 2% beryllium), bronze or brass in question. If the contact head and shaft are made of different materials, bronze, brass or copper-beryllium are particularly suitable for one material and steel or copper-beryllium for the other material. If the same materials are provided for the contact head and the shaft, the material can preferably be carbon steel or stainless steel or

CuBe. Carbon steel is preferred because it has good elasticity and low electrical resistance at a low cost. Since the welding points are created by melting the corresponding areas of the contact head and _shaft, which are due to the small size of the welding points and

the cold of the contact head and the shaft cool down very quickly when the welding beam is switched off,

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In the structure of the welds forming the weld point, processes can occur during cooling that they make hard and brittle. This is the case when the weld is made of hardenable steel or hardenable steel in for hardening when Contains sufficient cooling, especially carbon steel. This brittle

The ability to weld reduces the mechanical strength of the connection between the contact head and the shaft and can also adjust the electrical resistance of the contact bolt during operation by forming cracks in the weld.

let rise.

It is therefore provided according to a development of the invention, the brittleness and hardness of the To reduce the welding point. For this purpose it is provided according to a further development of the invention, that the shaft and / or the contact head, if it consists at least essentially of hardenable steel, is nickel-plated, with nickel in a layer thickness that thereby reduces the brittleness and hardness of the Sweat is reduced. If both the contact head and shaft are nickel plated, it is It is expedient that the total sum of this nickel layer is at least 5 µm, i.e. the thickness of the nickel layer on each of the two parts, for example at least

each is 2.5 ρ. If only one of the two parts 30th

is nickel-plated, the layer thickness of this nickel-plating is expediently at least 5 pounds. Such

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10

15th

20th

25th

30th

Nickel plating is also useful. If the contact head Law. the shaft is made of copper beryllium, as this increases the absorption of the laser beam during laser welding and the scattering of the strength of the Welded connection and the electrical resistance of the contact bolt is further reduced in series production *

It is particularly favorable for good mechanical strength of the connection between the contact head and shaft, especially in the case of bending stresses on the contact pin, as well as for constant electrical resistance of the contact pin if the hardness of the weld at the weld point is a maximum of 700 hv (Vickers hardness). _T his may through said plating of the shaft and / or contact head can be achieved.

In the event that the weld of the contact stud is made of hardenable steel

consists or contains hardenable steel to such an extent that it hardens and cools when the welding beam is switched off rapidly becomes brittle as a result, it can also be provided with particular advantage that the contact pin after the welding, a thermal aftertreatment causing the welds to be annealed to reduce the hardness and the brittleness of the weld. In particular this thermal post-treatment can be carried out in this way

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that the hardness of the weld after tempering is max. 7OG HV. The thermal aftertreatment can, in order to prevent changes to the surface of the contact pin, preferably in a vacuum or under protective gas take place. The tempering temperatures and the duration of the tempering have changed according to the weld and the desired one Decrease in their hardness and brittleness and can easily be determined on a case-by-case basis. In general, the event treatment can be several 100 ° C, for example 250-650 ° C, but also higher or lower. The tempering temperature can act on the contact pin, for example, for 1/2 to 2 hours. The contact bolt should cool down slowly after starting. Tempering will reduce the sweat tempered by changing their structure and loses hardness and brittleness, so that. it becomes more elastic and ductile and not 20th

more. too disadvantageous, increasing the electrical resistance Tends to crack or is less likely to crack.

Exemplary embodiments of the invention are shown in the drawing. Show it:

Fig. 1 is a partially sectioned side view of a spring contact pin of a non contacting device shown in more detail,

FIG. 2 shows an enlarged section from FIG. 1 /

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Pig. 3-7 each have a partially cut section from a contact bolt, which the contact head and a region of the shaft 2 inclined, each of these cutouts showing the respective state of the

Shows the contact bolt before welding

and the welding rays dash-dotted and those that can be generated by them from sweat existing weld points are indicated by dot-dash areas. 15th

The Pederkontaktstift 10 shown in Fig. 1 and 2 in a partially longitudinally sectioned side view is up to the execution . the metallic solid contact head 11 with the metallic solid shaft 12 of its contact bolt 13 connecting single weld point 14 of conventional design. The spring contact pin 10 consists of a metallic, cylindrical sleeve 15, a metallic compression spring 16 and the contact bolt 13 consisting of the shaft 12 and the contact head 11. The sleeve 15 and the contact bolt 13 are rotationally symmetrical. In many cases, the tip 11 * of the contact head can also expediently not be rotationally symmetrical, for example with indentations be provided that have particularly good contact with the point of an electronic, Test object 75 indicated by dash-dotted lines, such as a printed circuit board or the like, enable at which point this tip 11 * is pressed on by the pretensioned spring 16 loading the contact pin 13.

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The shaft 12 of the contact pin 13 consists of two 5

cylindrical sections 17,18 with different diameters, namely a piston-shaped section 17 which is permanently located completely in the sleeve 15 and the rod-like section 18, which is subsequently reduced in diameter and which is positively inserted into a central blind hole 19 of the head 11 and by means of the single welding point 14 with the Shank 12 is connected. This weld point 14 is an overlap weld point here, since it extends from the outer surface of the head 11 through its jacket encompassing the bore 19 ″ into the shaft 12 The outside of the head has a relatively large diameter. This diameter D ₅₁ is in the direction of

direction of the longitudinal axis 20 of this contact pin 13 measured significantly greater than half the value of the Diameter D. of the head at the welding point 14 corresponds, which is particularly favorable. This welding point 14 a maximum of one Drit ™ is sufficient in the shaft 12

tel of the diameter D of the shaft 12 on the weld

put in. In fact, here it has a penetration depth D into the shaft 12 of approximately 1/4 of the shaft diameter D _- . This means that the welding c

Point 14 having cross-sections of the shaft 12

The material is still much unchanged, which means that it was not melted during welding. The largest diameter D ^ of the welding point 14 is at least 1.5 times, preferably 2 to 4 times, here

about 2.5 times the depth D ₊ . of the welding point 35

in the contact pin 13.

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As a result, the electrical and mechanical properties of the contact pin 13 are very favorable.

The large diameter of the weld of the weld point 14, which diameter also at the transition point between the shaft 12 and the contact head 11 as a result of the calotte-like Shape the sweat is relatively large quickly, also causes

. small electrical contact resistance between the contact head 11 and the shaft 12. It is less electrical resistance of the contact pin 13 reached, this resistance in the series production of the contact pin from contact pin to; t contact pin only scatters slightly. Also is that

ζ mechanical strength of the connection between contact

A head 11 and shaft 12 high, as the flat wide sweat

ι «η point 14 of this welded connection high mechanical j gives strength and the risk of breakage even in the

Case that the Schvueißpunkt is brittle, only relatively

;. is low.

_oc Although electron beam welding or, in some cases, micro plasma welding is also possible, laser welding is preferred. Let it be-

, half hereinafter referred to laser welding.

In this case, the spot weld 14 became appropriate

"_ Generated by means of a defocused laser beam 21.

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This laser beam was 21, as if through the diverging ones Radiation arrows is indicated on

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focuses a focal point that cannot be seen, which was located a considerable distance in front of the surface of the contact head 11, so that this defocused laser beam 21 hit the contact head 11 during welding with a significantly reduced energy density compared to its energy density at the focal point. This results in the widening of the welding point 14 and its small penetration depth D _e into the shaft 12.

Instead of defocusing the laser beam by pressing 15

its focal point is in the beam direction in front of the contact head, it can also be provided that this The focal point is theoretically in the beam direction at a distance behind the contact head 11, where it

however, no longer occurs during welding because 20

the laser beam is shielded from this focal point by the contact pin 13. In that case they would the radiation arrows of the laser beam converge on the point of impact of the contact head 11,

instead of diverging as shown in FIG. 2 * 25

The only weld point 14 of the contact stud 13 in Figs. 1 and 2 is a lap weld point, i. caused by an overlap weld.

It is also possible to carry out the welding by means of a 30

make parallel laser beam, as in the embodiment according to Fig. 3 is shown. Everyone

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g of the two parallel laser beams 21 each cause one Throat welding. So you generate two in the contact pin 13 shown before the welding Fillet weld points 14, their approximate circumferences are indicated by dash-dotted lines in the sectional plane shown. This fillet weld is achieved in that the central, rotationally symmetrical blind hole 19 of the contact head 11 has a frustoconical enlargement 19 * at its start. which forms a bevel through which the frustoconical circumferential wall in this area extends the blind hole 19 at a distance from the massive. Shank 12 is located. The upper laser beam 21 acts on the Contact head 11 perpendicular to its rear peripheral edge area and melts it down and melts here the shaft 12 on. The lower laser beam 21 strikes the contact head 11 and the shaft 12 at an angle further area of the bevel and melts the relevant forehead area of the head 11 and melts the shaft 12 on. The melt created by this melting down and melting during welding forms the welds forming the relevant welding point 14 after their rapid solidification.

In the exemplary embodiment according to FIG. 3, two

moved diametrically 30 to one another on the longitudinal axis 20 of the shaft

opposing fillet weld points 14 generated, which are arranged at a distance from one another, in that both are already at a distance in front of the longitudinal center axis 20

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_ the shaft 12 ends.

In the embodiment of FIG. 4, a fillet weld is also made, namely here again by means of a diverging laser beam * les 21, which is directed diagonally towards the welding point iat. This fillet weld is achieved here in that at least one recess / here an annular groove 22 concentric to its long axis is let into the shaft 12. The rear forehead surface 23 of the contact head 11 is at the level of the middle of the annular groove 22 as shown. Of the The weld point 14 produced during welding has here a 3 penetration depth into the shaft 12, which is approximately a quarter of the diameter of the shaft

.. 1-2 corresponds to welding point 14, where this diameter is related to the shaft 12 before your welding. Further extends in this exemplary embodiment the weld point 14 produced during welding as a result

"Κ of the annular groove 22 over areas of the shaft 12 with two different diameters before the Welding. For each of these areas, however, the welding point 14 in each cross section of the shaft 12 passing through it is a maximum of one third of the original shaft diameter in this original, shown rotationally symmetricalep. shaft 12 penetrates.

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In the embodiment of FIG. 5, the massive contact head 11 of the contact pin 13, in contrast to the other execution examples no blind hole for

Insertion of the shaft 12, but its rear

. _i; wärtige end face 23 is flat and the solid shaft

is with a flat face to the End face 23 butt attached and is by means of a diverging laser beam 21 with the head 11 through a dot-dash weld point 14 tied together. This weld is a corner weld. For example, a point seam made of welding points that extends around the circumference of the contact bolt 13 cannot be seen can be formed, for example, three welding points can be provided which have approximately the same shape and whose center-to-center distances in relation to the longitudinal axis are approximately 120 °.

25th

The advantage of the embodiment of FIG. 5 is that

the contact head 11 does not require a blind hole and is therefore easier to manufacture.

₃ q In the embodiment of FIG. 6 this is in the

rear end face of the contact head 11 located blind hole 19 is formed only as a frustoconical countersink and the diverging laser beam

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produces a fillet weld point 14 that protrudes only flat into the solid shaft 3 2.

7 shows a particularly advantageous arrangement of two overlap weld points 14 of a contact

IQ bolt 13 shown. The centers of these weld points are arranged at an angular distance of 180 ° with respect to the longitudinal axis 20 of the contact bolt 33 and are offset from one another in the longitudinal direction of the contact bolt 13. The result is that the area of the material of the shaft 12 not covered by the welding points 14 is larger than when the welding points 14 are diametrically opposite one another

The laser beam 21 causes - in technical terms - when it creates a welding point, melting it (in the case of lap welding) or Melting down (in the case of corner or fillet welding) of the relevant jacket or edge material of the contact head and melting the relevant material of the shaft.

The shaft 12 is solid, at least in the longitudinal region having a weld point, that is to say has no cavity here. The shaft can preferably be completely solid _{Q 0.} However, it is also possible not to make it solid in at least one longitudinal area away from the weld point (s), for example to make it hollow in the area of the thickened piston 17 in FIG.

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In the exemplary embodiments according to FIGS. J-3 and 7, the wall thickness of the cylindrical blind bores 19 can preferably be a maximum of 0.4 mm, particularly expediently about 0.1 to 0.2 mm, because of the overlap welds present here. These wall thicknesses allow particularly tight tolerances for the welding points to be adhered to.

According to the invention, the penetration depth D of the sweat point. into the, shaft 3 2 of the contact pin Third of the shaft diameter before welding to the

, _ the intended welding point, but not more 15th

than max. 0.35 mm. So if the shaft diameter is so is large that a third of this shaft diameter is greater than 0.35 mm at the intended welding point, the penetration depth of the welding beam must not exceed this limit of 0.35 mm in the shaft. As already described, the penetration depths D of the welding point 14 into the shaft are approximately 0.1 to 0.2 mm very cheap.

In the exemplary embodiment according to FIG. 7, 25 furthermore begin

the two weld points on a tapered diameter area 60 of the contact head 11, so from the Area 61 of the maximum diameter as seen in a depression - possibly also as a channel, annular groove

Or the like. Can be designed - so that the ever 30th

Welds that bulge out according to materials do not protrude outward beyond the area 61 of the contact head 11, whereby the distances between adjacent contact bolts of the contacting device are minimally provided

can be. 35

Claims (1)

1. Contact bolt for an electrical contact member of one of the testing or measurement of electronic test items, such as circuit boards od Penetration depth (D _ß ) of the welding point (14) into the shank (12; max. D _c / 3 is, where D _{c is} the diameter of the shank (1?) Present before the welding at the relevant cross-section of the shank, measured in the direction of the The depth of the weld is, however, the penetration depth (D) of the weld point (14) in the shaft (12) is no more than 0.35 mm, and that the diameter of the shaft before welding at the intended weld point is a maximum of 3 mm. 2. Contact bolt according to claim 1, characterized in that the welding point is an OberlapprSchweißpunkt and that the largest diameter (D) of this upper lap weld point (14) at least J.5 <times its Depth (D ^) in the contact pin. ■ Ill I I I I - 2 - 3. Contact bolt according to claim 1, characterized in that the weld point is a fillet or corner weld point is. 4. Contact bolt according to one of the preceding ä, «Proverbs, characterized in that the penetration depth (D) of the welding point in the shaft (12) is approximately 0.1-0.2 mm amounts to. 5. Contact bolt according to one of the preceding claims, characterized in that the maximum diameter (D_) of the welding point (14) measured in the direction of the longitudinal axis (20) of the contact head (11) is greater
than half the outer diameter of the contact head on
Welding point. 6. Contact bolt according to one of the preceding claims, characterized in that at least two welding points (14) are arranged offset from one another in the direction of the longitudinal axis of the shaft (12). 7. Contact bolt according to claim 6, characterized in that that the axial offset of the two welding points
at least 0.2 mm, preferably at least 0.4 mm
amounts to. 8. Contact bolt according to one of the preceding claims, characterized in that in the case of an overlap welding point (14) its largest diameter (D _a ) is approximately 2 to 4 times the depth (D _t ) of the welding point in the contact bolt (13) *, • f »#i ι» · · 5572 9. Koittaktbolaen according to claim 6 or 7, characterized in that a total of two welding points (14) are provided, the centers of which, based on the 10. catch of the contact head, around 180 are arranged offset at an angle. to each other Contact bolt according to one of the preceding claims, characterized in that the shaft (12) and / or the contact head (11) at least essentially made of hardenable steel or copper-beryllium consists. Contact bolt according to Claim 10, characterized in that the shaft (12) and / or the contact head (11) are nickel-plated, the layer thickness of the nickel-plating preferably being at least 5 / tun. 12 .. Contact bolt according to claim 10 or 11, characterized in that the steel is a carbon steel. 13. Contact bolt according to one of the preceding claims, characterized in that the shaft (12) or the contact head (11) consists of bronze or brass. 14. Contact bolt according to one of the preceding claims, characterized in that the hardness of the Welding is a maximum of 700 HV. «■ ■ · t · · '"Ij 5572 15. Contact bolt according to one of claims 1-14, its shaft in a hole dee 5 Contact bolt is used, characterized in that the wall thickness of the bore (19) at the intended welding point (14), preferably forming an overlap welding point before welding is max. ο.4 mm, preferably about 0.1 to 0.2 mm. 16. 'Contact pin according to one of claims 1-15, characterized in that the center of gravity begins in a depression (60) in the contact head, in such a way that it does not protrude beyond the largest diameter of the contact head beyond the contact head. 17. Contact bolt that hardens at least partially-20 steel, according to one of the preceding Claims, characterized in that the welding of the at least one welding point (14) is hardened and tempered.