EP0188716B1 - Ball-point pen tip and its manufacturing method - Google Patents

Description

The invention relates to a ballpoint pen tip with a metal tube receiving the writing ball in a seat at its front end, the ball seat being formed by inwardly directed deformations of the metal tube formed as longitudinal grooves as part of the ink-guiding device and the longitudinal grooves ending in front of the ball-side end of the metal tube.

Such a ballpoint pen tip is known from FR-A-1 088 078, US-A-32 83 390 and from CH-A-351 188. The longitudinal grooves molded into the metal tube in these ballpoint pen tips each extend from the ball seat over part of the length of the metal tube. Thus, the ink or ink paste must first be transported over a certain distance before the capillary action of the sections located between these longitudinal grooves inside the metal tubes can take effect. In this case, only these longitudinal channels or the sections between them are provided for generating the capillarity, so that these previously known ballpoint pen tips are not suitable for liquid ink. Furthermore, a ballpoint pen with such a ballpoint pen tip must point downwards when writing, i.e. writing on a vertical surface or even on the underside of an object is not possible since the capillarity of these metal tubes is not sufficient to convey the ink paste upwards.

A ballpoint pen tip is known from DE-A-30 00 214, in which inward deformations in the area of the ball between its free writing area and the ink supply serve as a ball seat. These deformations are designed in such a way that they themselves produce a certain capillarity in the area of the ball. In the longitudinal direction of the metal tube, however, the extent of these deformations is so small that they cannot serve as longitudinal channels. For the supply of the liquid writing ink in this case, therefore, a guide pin arranged in the longitudinal direction of the metal tube is used with a strongly jagged cross section, which also has some play with respect to the inside of the metal tube in order to produce the desired capillary effect. This guide pin is complex due to its jagged cross-sectional shape. Furthermore, this DE-A-30 00 214 discloses, as an ink guide device, a fiber bundle in which part of the ink supply remains in the fibers, ie is not used.

A ballpoint pen tip with a bored hole instead of a metal tube is known from FR-A-965140. The bore is circular and smooth on the inside and has no inward-facing deformations, but only an out-of-round guide pin, which at the same time has to support the ball, i.e. it is loaded and supported in the longitudinal direction when writing. The cross-sectional shape of this guide pin is flattened or jagged one or more times, so that this entire solution is to be regarded as very complex due to the elaboration of the ink channel from the full and due to this complicated cross-sectional shape of the ink guide pin.

From FR-A-23 34 507 various ballpoint pen tips are known, in which the tube containing the ball preferably consists of plastic, so that after a very short time, wear on the tip must be expected. This tube either has short inward deformations and / or a jagged or even longitudinally corrugated ink guide pin or there are grooves machined in the longitudinal direction to form the required capillaries. In any case, there is again a very complex shape of the ink guide pin or tube.

From the same inventor from whom FR-A-23 34 507 originates, US-A-39 04 297 is known, which, although it discloses a guide pin which is substantially smooth in cross section or provided with a longitudinal groove, in which, however, the metal tube is either at all no deformation and. certainly has no longitudinal channel if the guide pin has the groove mentioned, or if the tube has soft grooves or the like incorporated into its internal cross section. which together with the guide pin form the desired capillaries. Thus, either an ink guide pin with a jagged cross-section or a very complex metal tube with a contoured inner cross-section is required.

FR-A-646 651 also shows a ballpoint pen tip, in which grooves or the like are made in the inside of a bore machined from the full. Capillaries are incorporated and an ink guide pin is not provided at all.

The object is therefore to create a ballpoint pen tip of the type and of the type mentioned at the beginning, in which the advantages of a deformed tube compared to machining the ballpoint pen tip are retained, but the ink guide device is simplified and is so effective that it can also be used for liquid writing ink without the need for a guide pin that is jagged or profiled in cross section.

The solution to this problem is that the longitudinal channels run over the entire long side of the metal tube up to the ball and that in the interior of the metal tube as an ink guide device between the inwardly shaped longitudinal channels a smooth on the outside of the guide pin is provided, which with the sections of the Metal tubes between the longitudinal channels form capillaries.

This results in a very simple ink guiding device in which the longitudinal channels, due to their expansion over the entire long side of the metal tube, lead directly from the ink source to the ball and can interact with a guide pin of very simple cross-section. Thus the longitudinal channels have a double function by not only form all or part of the spherical seat with their outlet, but also contribute to the supply of the ink or ink paste due to the improvement of the capillary action within the tube.

It is expedient if the longitudinal channels end in front of the end of the tube on the spherical side and their transitions from the inside to the outside of the original tube circumference serve as a spherical seat or part of the spherical seat. In this case, at least three longitudinal channels oriented parallel to its axis can be arranged on the circumference of the tube, preferably evenly distributed. To increase the capillarity, even more such longitudinal channels, e.g. four such longitudinal channels can be provided.

As already mentioned, the integrally formed longitudinal channels inside the tube itself can serve as an ink conductor. This is particularly useful for pasty ink.

An embodiment of the ballpoint pen tip according to the invention for pasty ink with longitudinal channels as an ink-guiding device can consist in that the longitudinal channels in the interior of the tube are sharp-edged and thus have a high capillary shape, in particular at the transition of the tube cross-section to the cross-section of the respective longitudinal channel. With a relatively short tube, sufficient capillary action can be achieved in order to be able to write at least briefly on a vertical surface or even on an underside.

The guide pin can have a full cross section and preferably be circular in cross section. This makes this guide pin very easy and simple to manufacture. In particular, the guide pin can be clamped between the channel-shaped deformations or longitudinal channels distributed around the circumference of the tube. There is then no need for any additional stops or brackets for this guide pin, which additionally forms highly capillary gaps with the somewhat inwardly curved or shaped longitudinal channels in the immediate vicinity of the contact points.

The smooth guide pin can rest with its face against the ball of the ballpoint pen tip and form an abutment for it in the axial direction. This guide pin, especially if it is clamped in the manner already mentioned by the longitudinal channels, becomes an additional component of the ball seat.

This effect can be improved if the guide pin has a depression on its end face facing the ball and in contact with it, in which the ball engages in the position of use.

The guide pin can consist of plastic and / or metal, preferably of a cylindrical wire section. This makes its manufacture and assembly very easy.

The longitudinal grooves of the tube can extend from the end remote from the ball to the front side of the tube and end with it, and are preferably in contact with an ink wick and / or an ink cartridge. This ensures that the ink is captured by the ink-guiding device directly at the entry into the tube away from the ball, be it the longitudinal channels alone or the longitudinal channels in connection with a guide pin, and is transported to the ball by the capillary action.

A modified embodiment of the ballpoint pen tip can consist in that between the ball seat and the ball-side end of the guide pin an inward projection on the tube, in particular an annular bead, is formed or compressed, which forms a distance with a capillary effect between the ball and the guide pin . In the various embodiments of the invention described above, the end of the tube remote from the ball can have an extension for direct connection to an ink space, preferably with writing paste, or to a wick system for aqueous ink.

Especially when combining one or more of the features and measures described above, there is a ballpoint pen tip with a metal tube with deformations, in which these deformations are not used exclusively to form the ball seat and, if necessary, to produce a capillarity effective in the area of the ball, but also for the supply line the ink contribute to the ball seat. If a guide pin is used, a guide pin with a very simple cross-section is advantageously possible, which is a considerable advantage over the small dimensions of such a metal tube compared to a jagged guide pin with a complicated cross-section.

The invention also relates to a method for producing a ballpoint pen tip of the type described above.

This method is primarily characterized in that a tube which is initially circular in cross section is simultaneously hammered and / or pressed on its outside by shapes provided with rib-like longitudinal projections.

When molding the longitudinal channels or the like. a pin-shaped body can be inserted or inserted into the interior of the tube to limit the indentations. When the longitudinal channels are formed, a pin with a circular cross section can engage in the tube, which is pulled out after the longitudinal channels have been formed. This has the advantage that the necessary space is reserved from the outset for a guide pin of the cross section, which corresponds to the abutment pin when deforming.

With the pin engaging in the tube during deformation, the spherical seat can also be formed simultaneously or subsequently by an axial movement of this pin deeper into the tube by means of a preferably conical cross-sectional enlargement of this pin located in the end region of the tube.

However, it is also possible that the guide pin is already on before the longitudinal grooves are formed set and underpinned by a retaining pin at the end remote from the ball and held in the correct position and preferably a conical stamp on the end face for expanding the ball seat is pressed into the ball end face of the tube during or after the shaping of the longitudinal grooves. As a result, the guide pin is clamped between them as soon as the longitudinal channels are formed and no longer has to be installed subsequently.

The invention is described in more detail below with its details that are essential to it, using the drawing in several exemplary embodiments.

• Fig. 1 einen Längsschnitt durch eine erfindungsgemässe Kugelschreiberspitze mit einem an seinem Ende noch einen Adapter aufweisenden Röhrchen, bei weichem eingeformte Längsrinnen gleichzeitig mit ihrem kugelseitigen Ende den Kugelsitz bilden,
• Fig. 2 eine der Fig. 1 entsprechende Darstellung, bei welcher ein Leitstift die Kugel unterstützt und mit seiner Stirnseite ein Teil des Kugelsitzes bildet,
• Fig. 3 einen Querschnitt des Röhrchens gemäss der Linie A-A in Fig. 1 und 2,
• Fig. 4 eine Stirnansicht der erfindungsgemässen Kugelschreiberspitze ohne die Kugel und ohne den Leitstift mit Blick auf die stirnseitigen Enden und Übergänge der Längsrinnen, die den Kugelsitz bilden,
• Fig. 5 in vergrösserter Darstellung eine abgewandelte Ausführungsform der erfindungsgemässen Kugelschreiberspitze, bei welcher zwischen dem Leitstift und der Kugel ein nach innen gerichteter Wulst als Abstandhalter zur Erzeugung einer Kapillarität unter der Kugel vorgesehen ist,
• Fig. 6 einen der Fig. 5 entsprechenden Längsschnitt durch die Kugelschreiberspitze, bei welcher der Leitstift eine Einsenkung als Teil des Kugelsitzes hat,
• Fig. 7 ein Ausführungsbeispiel, bei welchem das die Kugelspitze bildende Metallröhrchen bis zu einem Tintenleiter ragt, wobei das kugelferne Ende des Röhrchens und der Tintenleiter von einem Adapter umschlossen sind,
• Fig. 8 einen Längsschnitt durch eine Kugelschreiberspitze mit Längsrinnen, die mit einer kugelfernen Erweiterung an eine Pastenmine angeschlossen ist,
• Fig. 9 eine der Fig. 8 entsprechende Darstellung, bei welchem die Erweiterung des Röhrchens an ein Patronensystem, insbesondere ein Dochtsystem angeschlossen ist,
• Fig. 10 einen Querschnitt der Röhrchen und der eingeformten Längsrinnen gemäss den Linien B-B in Fig. 8 und 9, wobei scharfkantig ausgeprägte hochkapillare Längsrinnen vorgesehen sind,
• Fig. 11 in schematisierter Darstellung den Beginn des Verformens des Röhrchens, wobei ein Stift in das Innere des Röhrchens eingreift, bevor die Former die Längsrinnen anbringen,
• Fig. 12 im Querschnitt das Anformen von insgesamt vier Längsrinnen nach dem Zustellen der Former,
• Fig. 13 eine Seitenansicht zweier Former nach dem Anformen der Längsrinnen gemäss Fig. 12 mit Längsschnitt durch das Röhrchen und den von den Formern nicht erfassten Kugelsitz,
• Fig. 14 einen Längsschnitt durch ein noch nicht mit den Verformungen versehenes Röhrchen kurz vor dem Zustellen der Former für die Längsrinnen, wobei im Inneren des Röhrchens bereits ein Tintenleitstift angeordnet ist und zur Formung des Kugelsitzes ein eigener Stempel vorgesehen ist,
• Fig. 15 einen Querschnitt durch drei Former und den gleichzeitig im Inneren des Röhrchens befindlichen Stift nach dem Anbringen der Längsrinnen sowie
• Fig. 16 einen Längsschnitt durch das geformte Röhrchen gemäss den Linien C-C in Fig. 15.

It shows in a partially schematic representation:

• 1 shows a longitudinal section through a ballpoint pen tip according to the invention with a tube at its end also having an adapter, in the case of soft molded-in longitudinal grooves simultaneously forming the ball seat with its ball-side end,
• 2 shows a representation corresponding to FIG. 1, in which a guide pin supports the ball and forms part of the ball seat with its end face,
• 3 shows a cross section of the tube along the line AA in FIGS. 1 and 2,
• 4 shows an end view of the ballpoint pen tip according to the invention without the ball and without the guide pin with a view of the front ends and transitions of the longitudinal channels which form the ball seat,
• 5 is an enlarged view of a modified embodiment of the ballpoint pen tip according to the invention, in which an inwardly directed bead is provided between the guide pin and the ball as a spacer for generating capillarity under the ball,
• 6 shows a longitudinal section corresponding to FIG. 5 through the ballpoint pen tip, in which the guide pin has a depression as part of the ball seat,
• 7 shows an exemplary embodiment in which the metal tube forming the ball tip protrudes up to an ink conductor, the end of the tube remote from the ball and the ink conductor being enclosed by an adapter,
• 8 shows a longitudinal section through a ballpoint pen tip with longitudinal channels which is connected to a paste lead with an extension remote from the ball,
• 9 shows a representation corresponding to FIG. 8, in which the extension of the tube is connected to a cartridge system, in particular a wick system,
• 10 shows a cross section of the tubes and the molded-in longitudinal channels according to the lines BB in FIGS. 8 and 9, wherein pronounced, highly capillary longitudinal channels are provided,
• 11 shows a schematic representation of the beginning of the deformation of the tube, a pin engaging the interior of the tube before the formers attach the longitudinal channels,
• 12 shows in cross section the molding of a total of four longitudinal channels after the shapers have been fed in,
• 13 is a side view of two formers after forming the longitudinal channels according to FIG. 12 with a longitudinal section through the tube and the ball seat not covered by the formers,
• 14 shows a longitudinal section through a tube not yet provided with the deformations shortly before the shapers for the longitudinal channels are brought in, an ink guide pin already being arranged in the interior of the tube and a separate stamp being provided for shaping the ball seat,
• Fig. 15 shows a cross section through three formers and the pin located inside the tube at the same time after attaching the longitudinal channels and
• 16 shows a longitudinal section through the shaped tube according to the lines CC in FIG. 15.

According to the above list of figures, the drawings show different embodiments of a ballpoint pen tip 1, which, however, like the parts that correspond in each case, is given the same reference numerals in the different exemplary embodiments.

In all exemplary embodiments, the ballpoint pen tip 1 has a metal tube 2, which receives the writing ball 4 in a ball seat 5 at the front end 3. Arranged in the interior of the metal tube 2 is an ink-guiding device which is configured differently in the exemplary embodiments and extends over its entire length. The ball seat can also be designed differently in the various embodiments in a manner to be described, but is in each case wholly or partly formed by inward deformations of the tube 2.

In all exemplary embodiments, these deformations on the tube 2 are longitudinal grooves 6 extending over its entire longitudinal side up to the ball 4, which at the same time form the ink-guiding device or a part thereof in the tube 2.

The longitudinal channels 6 end in front of the ball-side end 3 of the tube 2 and their transitions 7 from the inside to the outside to the original tube circumference serve as a ball seat 5 or part of this ball seat 5. They serve alone as a ball seat in the exemplary embodiments according to FIGS. 1, 5 and 7 to 9. In Fig. 2 and 6 they serve only as part of the ball seat, because a guide pin 8 to be described lies with its end face 9 on the ball 4 of the ballpoint pen tip 1 and forms an abutment for it in the axial direction, i.e. with it End face 9 belongs to the ball seat 5.

3 and 15, at least three longitudinal channels 6 oriented parallel to its axis can be arranged uniformly distributed on the circumference of the tube 2. 10, however, there may also be more, for example four longitudinal channels 6.

In the embodiment according to Figures 8 to 10, the integrally formed longitudinal channels 6 in the interior of the tube 2 themselves serve as an ink guide or ink guide device. They are sharp-edged in the interior of the tube 2, in particular at the transition 10 of the tube's external cross-section to the cross-section of the respective longitudinal channel 6, and are thus highly capillary-shaped. The capillarity is further promoted by the fact that in the case of FIG. 10 there are more such longitudinal channels 6, which are therefore narrower in terms of the overall cross section.

In the other exemplary embodiments, the aforementioned guide pin 8 is provided in the interior of the tube 2 as an ink-guiding device or part thereof between the inwardly shaped longitudinal grooves 6, which is advantageously smooth on its outside, i.e. without grooves, deformations and fissures and forms 6 capillaries with at least the radially innermost surface line or surface of the longitudinal channels. 2 and 3 that the intermediate space 11 on the one hand between two adjacent longitudinal grooves 6 and on the other hand this guide pin 8 is very narrow and in the area of contact of the longitudinal grooves 6 with the guide pin 8 has conical constrictions which result in a good capillary action. This embodiment is therefore also suitable for liquid ink in which the supply to the ball must be made with even narrower capillaries than with pasty ink.

In Fig. 6 can be seen an embodiment in which the guide pin 8 on its side facing the ball 4 and with this side in contact end face 9 has a recess 12 into which the ball 4 in Gebraüchsstellung ^- engages. In addition, enough capillary spaces 13 are nevertheless formed in order to lead the ink well to the ball 4.

In the other embodiments, the end face 9 of the guide pin 8 maintains a slight distance from the ball 4, which also has a capillary effect and contributes to the supply of the ink to the ball.

An embodiment is indicated in Fig. 5, in which between the ball seat 5 and the ball-side end 9 of the guide pin 8, an inward projection on the tube 2, in this case an annular bead 14 is molded or compressed between the ball 4 and the guide pin 8 forms the mentioned distance with capillary action.

In all cases shown, the guide pin 8 has a full cross section that is circular. Compared to a jagged guide pin provided with longitudinal grooves or undercuts, such a smooth guide pin with a simple full cross section can be manufactured much more easily and can also be introduced more easily into the very narrow and small tube. The guide pin can consist of plastic or metal, for example a cylindrical wire section.

Fig. 7 shows an embodiment in which the longitudinal grooves 6 of the tube 2 at the end remote from the ball extend into the end face 15 of the tube 2 and end with it and e.g. be in contact with an ink wick 16 or an ink cartridge. This area can then be enclosed by an adapter 17.

In the embodiments according to FIGS. 1, 2 and 8 and 9, the end of the tube 2 remote from the ball has an extension 18 for direct connection to an ink space 19 or an ink conductor 16, whereby writing paste or a wick system for aqueous ink can be provided.

It should also be mentioned that for fixing the guide pin 8, in particular when it also forms an abutment for the ball according to FIG. 2 or 6 and it is not itself supported by an ink conductor 16, or in addition to this, the guide pin 8 between the Longitudinal channels 6 can be clamped.

The manufacturing method of the above-described exemplary embodiments of a ballpoint pen tip can be seen from FIGS. 11 to 16.

In the manufacture of the ballpoint pen tips 1 described above, the procedure is such that a tube 2, initially circular in cross section, is simultaneously hammered and / or pressed on its outside by shapers 21 provided with rib-like longitudinal projections 20. The end position according to FIGS. 12 and 13 is taken from the starting position according to FIG. 11 and the end position according to FIGS. 15 and 16 from the starting position according to FIG. 14. The rib-like longitudinal projections 20 of the former 21 then form the longitudinal channels 6.

When the longitudinal channels 6 are molded into the interior of the tube 2, a pin-shaped body 22 is simultaneously inserted or inserted to limit the recesses, as can be seen in FIGS. 11 to 13 and in a modified form also in FIGS. 14 and 15. As a result, the space for the guide pin 8 or else the interior space between the longitudinal channels according to FIG. 10 is kept free.

In the method according to FIGS. 11 to 13, when the longitudinal channels 6 are formed, a pin 22 with a circular cross section engages in the tube 2, which is pulled out after the longitudinal channels 6 have been formed. With this pin 22, which engages in the tube 2 during the shaping, the spherical seat 5 is also simultaneously or subsequently shaped deeper into the tube 2 by means of an axial movement of this pin 22 by means of a conical cross-sectional enlargement 23 located in the end region of the tube 2.

Although the longitudinal projections 20 of the former 21 are shorter than the region of the tube 2 to be deformed, so that the end face of the tube that later forms the spherical seat is not acted upon from the outset, there is however the possibility that the deformation forces radiate into this region, which is why a final one Forming the ball seat 5 by means of the cross-sectional widening 23 of the pin 22 is appropriate.

The method shown in FIGS. 14 to 16 is basically the same as that of FIGS. 11 to 13 from. Before the longitudinal channels 6 are formed, however, the guide pin 8 is already inserted into the tube and is gripped by a retaining pin 24 at the end remote from the ball. In addition, a conical stamp 25 on the end face is provided for expanding the ball seat 5 during or after the shaping of the longitudinal grooves 6, which is pressed into the end face of the tube 2 on the ball side to form or finally form the ball seat 5. At the same time, the guide pin 8 is thus already brought to its point of use, and it also forms the inner abutment for the deformations.

All features and construction details shown in the description, the summary, the claims and the drawing can have significant meaning both individually and in any combination with one another.

Claims (18)

1. A ball-point pen tip (1) with a metal tube (2) receiving the writing ball (4) in a socket (5) at the front end (3) of said tip, the ball socket (5) being composed by deformations of the metal tube (2) which are inwardly directed and take the form of longitudinal channels (6) as part of the ink conducting means and the longitudinal channels (6) ending in front of the metal tube-end (3) at the ball side, characterized in that the longitudinal channels (6) extend over the entire longitudinal side of the metal tube (2) up to the ball (4) and that in the form of an ink conducting means there is provided inside the metal tube, between the inwardly shaped longitudinal channels (6), a conducting pin (8) which is smooth on its outside and forms capillaries together with the segments of the metal tube (2) between the longitudinal channels (6).

2. The ball-point pen tip as claimed in claim 1, characterized in that the longitudinal channels (6) end in front of the tube-end (3) at the ball side and their transitions (7) from the inside to the outside to the original circumference of the tube serve as the ball socket (5) or as part of the ball socket (5).

3. The ball-point pen tip as claimed in claim 1 or claim 2, characterized in that at least three longitudinal channels (6) are disposed so as preferably to be evenly distributed on the circumference of the tube (2) and are oriented parallel to the axis of the latter.

4. The ball-point pen tip as claimed in any one of claims 1 to 3, characterized in that the longitudinal channels (6) formed on the interior of the tube (2) themselves serve as ink conductors.

5. The ball-point pen tip as claimed in any one of claims 1 to 4, characterized in that the longitudinal channels are shaped to be sharp-edged and thereby highly capillary inside the tube (2), in particular at the transition (10) of the outer cross section of the tube to the cross section of the respective longitudinal channel (6).

6. The ball-point pen tip as claimed in any one of claims 1 to 5, characterized in that the smooth conducting pin (8) rests with its end face (9) against the ball (4) of the ball-point pen tip (1) and forms an abutment for said ball in the axial direction.

7. The ball-point pen tip as claimed in any one of claims 1 to 6, characterized in that the conducting pin (8) has on its end face (9) turned towards and contacting the ball (4) a depression (12) into which the ball (4) engages in the position for use.

8. The ball-point pen tip as claimed in any one of claims 1 to 7, characterized in that the conducting pin (8) has a solid section and is preferably circular in cross section.

9. The ball-point pen tip as claimed in any one of claims 1 to 8, characterized in that the conducting pin (8) is made of plastic and/or of metal, preferably of a cylindrical wire cutting.

10. The ball-point pen tip as claimed in any one of the preceding claims, characterized in that at the end remote from the ball the longitudinal channels (6) of the tube (2) extend into the end face (15) of the tube (2) and terminate therewith and preferably are in contact with an ink wick (16) and/or an ink cartridge.

11. The ball-point pen tip as claimed in any one of claims 1 to 10, characterized in that between the ball socket (5) and the conducting pin-end (9) at the ball side there is an inwardly directed projection, in particular an annular bead (14), formed onto the tube (2) and composes between the ball (4) and the conducting pin (8) a distance with capillary action.

12. The ball-point pen tip as claimed in any one of claims 1 to 11, characterized in that the tube-end remote from the ball has a widening (18) for direct connection to an ink reservoir (19) or ink conductor (16) preferably with writing paste or to a wick system for aqueous ink.

13. The ball-point pen tip as claimed in any one of the preceding claims, characterized in that the conducting pin (8) is wedged in between the longitudinal channels (6) distributed on the circumference of the tube.

14. A method of manufacturing a ball-point pen tip according to any one of the preceding claims, characterized in that a tube (2) initially circular in cross section is simultaneously hammered and/or pressed on its outside by forming means (21) provided with rib-like longitudinal projections (20).

15. The method as claimed. in claim 14, characterized in that as the longitudinal channels (6) are being formed a pin-like body (22) is driven into or inserted into the inside of the tube (2) to limit the inward deformation.

16. The method as claimed in claim 14 or claim 15, characterized in that as the longitudinal channels (6) are being formed a pin (22) circular in cross section engages in the tube (2) and is withdrawn after the longitudinal channels (6) have been formed.

17. The method as claimed in any one of claims 14 to 16, characterized in that using the pin (22) engaging in the tube (2) during deformation, the ball socket (5) is simultaneously or subsequently formed through axially moving said pin (22) deeper into the tube (2), the ball socket being formed by means of a cross sectional enlargement (23), preferably conical, located on the pin in the end region of the tube (2).

18. The method as claimed in any one of claims 14 to 17, characterized in that the conducting pin (8) is inserted before the longitudinal channels (6) are formed and a holding pin (24) engages under it at the end remote from the ball and preferably a punch (25) conical on its end face is urged into the end face of the tube (2) at the ball side to expand the ball socket (5) as or after the longitudinal channels (6) are formed.

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