EP0066541B1 - Method for the production of a ball tip for a liquid ink writing instrument, and tip produced by this method - Google Patents

Abstract

A slender tube (A) having an internal diameter of about 1 mm and a wall thickness of about 0.1 mm is used for the production of the tips of ball-point pens. After a cycle of combined linear and rotation-derived working steps, the tip has a front cross section (A') the internal diameter of which has been reduced to approximately the cross section of the ball (5); a central cross section (A''') the cross section of which corresponds to that of the original tube; and a rear cross section (A'') with a cross section larger than the preceding cross section (A'''). The seat (S) against which the ball (5) is supported consists of conical recesses. The seat (S) is traversed by an opening into which penetrates the end (3') of a needle-like part (3), which part effects the ink transfer from a reservoir (2) to the ball.

Description

The invention relates to a tip for a ballpoint pen which is fed with liquid ink and a method for its production.

Pens with pasty ink are known. These have the disadvantage of often forming stains at the start of writing.

Felt-tip pens are also known, in which the liquid ink of the writing tip is delivered by means of a tampon or pad.

Ballpoint pens with liquid ink are also known (see, for example, CH-PS 351 188), in which the ink in the direction of the ball by means of a ball made of fiber material and then a pointed object made of fibers, which is encased by a non-porous tube , is delivered.

However, these pens have the disadvantage that the discharge of the ink often stops, as a result of which air enters between the ink and the ball and the writing becomes impossible to continue.

In this connection, a ballpoint pen is known according to US Pat. No. 3,960,455, with a tip made of metal and for receiving two balls. The paste-like ink is supplied in a conventional manner, i. H. without the use of a memory in the form of a lump and needle-shaped pen for the capillary supply of the ink up to the ball. According to US Pat. No. 2,879,586 (Fehling), the tip consists of a tubular part with a strong wall and the same cross section throughout, which cross section corresponds to the diameter of the ball. The wall of the bearing point of the ball is not solidified and not reduced at the same time.

In the Fehling patent and in US Pat. No. 3,162,941 (Young), a tool is also specified which has the task of producing indentations for the seat of the ball. This object is achieved in part in a manner which is also equivalent to the present invention, taking into account that the two patents just mentioned have expired, i. H. are now common property.

DE-PS 870 962 describes a ballpoint pen for liquid ink with warts as an attachment for the ball. Here, the path for supplying the ink to the ball from the container is very long. The tip only has a diameter that corresponds to that of the ball. The supply of liquid ink to the ball described in CH-PS 562 106 takes place through a long channel; the ball is also stored in a plastic tip. The tip according to DE-OS 2 701 694 consists of plastic material. The needle-shaped pin ends far away from the ball. The accumulation of ink also forms here. The risk of air being sucked in and consequently the ink supply to the ball being suspended is very great. Finally, DE-OS 3000214 describes a tip with a tubular part made of metal, which is generally cylindrical and always made with the same cross-section.

The bearing of the ball is not solidified and is also designed with a reduced wall. In addition, the feed channel corresponds to the diameter of the ball and is therefore extremely small, in such a way that it is impossible to feed the ink by means of a fibrous pen up to very close to the ball.

The object of the invention is a tip for ballpoint pens of the latter type, in which these disadvantages are prevented, such as a method for their production.

The tip is characterized by the characterizing part of the first claim, the method by the characterizing part of claim 7.

• Fig. 1 zeigt schematisch einen Schnitt in größerem Maßstab des vorderen Teils eines Kugelschreibers;
• Fig. 2 zeigt schematisch die Aufeinanderfolge der Arbeitsgänge zur Herstellung der Spitze, ausgehend von einem zylindrischen Röhrchen;
• Fig. 3 zeigt das Arbeitsprinzip eines Gerätes, für die Verformung eines Röhrchens durch Rollvorgang;
• Fig. 4 zeigt wie der vordere Teil der Spitze auf ein genaues Maß gebracht wird;
• Fig. 5 zeigt, in größerem Maßstab, wie die ringförmige Halterung der Kugel hergestellt wird;
• Fig. 6 zeigt den Axialschnitt eines Werkzeugs in größerem Maßstab zum Bilden des Kugelsitzes;
• Fig. 7 ist ein teilweiser Schnitt durch eine Einheit zur Ausführung einer als Kugelsitz dienenden Einbuchtung.

A preferred embodiment of the invention is described in more detail below with reference to the accompanying drawings.

• Fig. 1 shows schematically a section on a larger scale of the front part of a ballpoint pen;
• Fig. 2 shows schematically the sequence of operations for producing the tip, starting from a cylindrical tube;
• Fig. 3 shows the principle of operation of a device for the deformation of a tube by rolling;
• Fig. 4 shows how the front part of the tip is brought to an exact measure;
• Fig. 5 shows, on a larger scale, how the ring-shaped holder of the ball is made;
• Fig. 6 shows the axial section of a tool on a larger scale for forming the ball seat;
• Fig. 7 is a partial section through a unit for executing a recess serving as a ball seat.

Referring to the drawings, the tip is obtained from a tube known commercially as a "micro-tube" and used, for example, for the manufacture of hollow needles for syringes, catheters and the like. Like. Finds use.

This type of pipe is obtained from a metal strip, in particular from rust-resistant rolled steel, which is rolled up and welded in the longitudinal direction. The thickness of the band is about 0.1 mm and the inside diameter of the raw tube available on the market is about 1 mm.

Fig. 1 shows schematically the tip of a ballpoint pen fed with liquid ink according to the invention. 1 shows the outer cylindrical body with the taper 1 'on the side of the ball.

The body 1 contains a small cylinder or pad 2 made of felt or spongy material of a known type, which has the task of an ink reservoir. The ink is of the type found in conventional fountain pens, with the fluidity not particularly dependent on the temperature differences can be influenced.

In its front end region, a cylindrical or needle-shaped part 3, which consists of fibers made of plastic or of equal material, is introduced in a force-locking manner. This also has a circular cross section, the end region 3 'of which is preferably designed with a reduced circular cross section in the direction of the ball.

The tip 4 provided with ball 5 is introduced into the tapered front end region 1 'of the body 1. The ball is fed with the ink sucked up by the bulk 2 by means of the needle-shaped part 3 by capillarity.

As can be seen from FIG. 1 on a larger scale, the needle-shaped part 3 with its end region 3 ′ comes very close to the ball 5. The distance "a" is very small, i. H. in such a way that the fibers are prevented from touching the ball or the fibers cannot get between the ball surface and the bearing seat S of the ball.

Advantageously, the distance "a" is smaller than _^3/4 of the sphere diameter, however, by _^1/4 is larger than the ball.

According to the invention, the end face 3 "of the needle-shaped part 3, i.e. the surface which causes a plurality of liquid filaments to flow out of the needle-shaped part, is thus brought into the seat S of the ball, the latter seat of which will be explained in more detail below.

Always with reference to FIG. 1, the inside diameter d of the end region 3 'of the needle-shaped part 3 is chosen to be as large as possible with respect to the ball diameter.

As a result, a number of capillary-shaped channels for guiding the ink and a storage of liquid, which is delivered from the bulk 2 to the needle-shaped part 3, are brought close to the associated spherical cap of the ball 5.

The diameter of the needle-shaped part is also designed to be as large as possible.

The path that the fluid travels in the needle-shaped part is advantageously chosen to be short.

This ensures that the ball is fed with ink which is drawn by capillary action from the needle-shaped part, the corresponding spherical cap being constantly wetted with the ink which accumulates between the front surface area 3 ″ and the ball.

Due to rotation of the ball, d. H. when it is in contact with the writing paper, the full surface of the ball is wetted and ink is continuously applied to the paper.

The needle-shaped part 3 thus fulfills a very important task. In fact, the features of its shape and the material used to manufacture it are chosen so that the ink is continuously supplied to the ball in the required amount, according to the intensity of writing.

Should the supply of ink not be sufficient and be such that it does not meet the current requirement, the interruption would result in air being sucked in and consequently the dispensing of the ink stopped.

• a) Trennen des Rohrteils aus Stahl, mit Vorteil aus rostbeständigem Stahl, und Entgraten der Ränder der beiden Stirnseiten,
• b) Verjüngen, durch Walzen des Endbereichs, des vorderen Teils des Röhrchens für die Lagerung der Kugel, wobei im rückwärtigen Teil des Röhrchens ein Stößel eingebracht ist der bis an die in Ausführung begriffene Verjüngung bewegt wird;
• c) Verringerung, durch radiales Rotieren und Walzen, des zuvor verjüngten vorderen Teils des Röhrchens, wobei die Längsachse des vorderen Teils derart gesichert ist, daß sie mit dem restlichen Teil des Röhrchens koaxial liegt,
• d) Erweitern des rückwärtigen Teils des Röhrchens, wobei der Innendurchmesser und der Außendurchmesser des zwischen dem vorderen Teil und dem rückwärtigen Teil liegenden Rohrbereichs wenigstens annähernd dem ursprünglichen Durchmesser entspricht,
• e) die dem vorderen und dem rückwärtigen Teil des Röhrchens zugehörigen zylindrischen Bohrungen auf ein genaues Maß bringen,
• f) gleichzeitig inneres und äußeres Walzen des vorderen Teils des Röhrchens mit einem als »Drilling« benannten Werkzeug, mit daraus sich ergebender Verringerung der Wandstärke und dessen Verlängerung,
• g) Ausführung des Kugelsitzes mit Hilfe von zentral wirkenden Stempeln mit konisch ausgebildeter Spitze, wobei der Kugelsitz aus Einbuchtungen besteht deren Spitze in Richtung der Achse des Röhrchens sich erstreckt, und darauffolgendem Egalisieren der Stützpunkte für die Kugel mit Hilfe eines Stößels der koaxial zu der Achse des Röhrchens wirkt,
• h) den äußeren Endbereich des Röhrchens, insbesondere den vor dem Kugelsitz angeordneten Teil mit Hilfe eines als »Drilling« benannten Werkzeugs gleichzeitig von Innen und von Außen auf ein genaues Maß bringen, wobei für diesen Arbeitsgang der Zapfen für die Kalibrierung von Innen, mit Bezug auf die den Kugelsitz darstellenden Stellen, zentriert ist,
• i) Abtrennen des Endes I des vorderen Teils, welcher infolge den vorausgehenden Bearbeitungen des Röhrchens überschüssig geworden ist,
• k) Herstellung des Randbereichs oder Kreisringes für das spätere Aufliegen der Kugel,
• 1) Umbiegen des Randbereichs nach Innen,
• m) Einbringen der Kugel durch Einschnappen infolge Vorhandenseins der nachgiebigen, ringförmigen Umbiegung im äußersten Bereich der Spitze (in den Zeichnungen nicht gezeigt).

Fig. 2 shows the different processes, ie the sequence of those processes that ensure the manufacture of the tip. The operations, which each ensure that the corresponding pipe part is held in place with the aid of a collet P, are as follows:

• a) separating the tubular part from steel, advantageously from rust-resistant steel, and deburring the edges of the two end faces,
• b) tapering, by rolling the end region, of the front part of the tube for the storage of the ball, a plunger being introduced into the rear part of the tube and being moved to the tapering which is being carried out;
• c) reduction, by radial rotation and rolling, of the previously tapered front part of the tube, the longitudinal axis of the front part being secured in such a way that it lies coaxially with the remaining part of the tube,
• d) widening the rear part of the tube, the inner diameter and the outer diameter of the tube region lying between the front part and the rear part corresponding at least approximately to the original diameter,
• e) bring the cylindrical bores associated with the front and rear part of the tube to an exact size,
• f) simultaneous inner and outer rolling of the front part of the tube with a tool called "drilling", with the resultant reduction in wall thickness and its extension,
• g) Execution of the ball seat with the aid of centrally acting punches with a conical tip, the ball seat consisting of indentations whose tip extends in the direction of the axis of the tube, and then leveling the support points for the ball with the aid of a plunger coaxial to the axis the tube works,
• h) at the same time bring the inside and outside of the tube, in particular the part in front of the ball seat, with the help of a tool called "drilling" to an exact size, for this operation the pin for the calibration from the inside, with reference centered on the positions representing the ball seat,
• i) severing the end I of the front part, which has become excess as a result of the previous processing of the tube,
• k) production of the edge area or circular ring for the later contact of the ball,
• 1) bending the edge area inwards,
• m) Inserting the ball by snapping due to the presence of the compliant, annular bend in the extreme area of the tip (not shown in the drawings).

With regard to the sequence of operations for the manufacture of the tip, a tube of extremely thin wall thickness is assumed, this tube is reduced in the front part by cold working until the internal dimension comes close to the diameter of the ball; then extends the rear, d. H. the end region opposite the front part until an inner cross-section is reached which can take up a part of the needle-shaped part and this ensures that it can penetrate very close to the ball, the part N "interposed between the front part A 'and the rear part A" having its original cross-section maintains.

The deformation work, in particular with regard to the front part of the tube, apart from the production of the inside diameter required for receiving the ball, also a consolidation and a reduction in the original wall thickness in order to facilitate the insertion and the elastic yielding required for the ball to snap into place to ensure the edge area. This prevents premature wear of the entire ball bearing surface by giving the material the required hardness.

This combination of narrowing and expansion of the opposite parts of a tube with respect to an average dimension of the same, such as the production of a centrally arranged passage, which is delimited by a plurality of conically shaped indentations as a seat for the ball, and finally the reduction of the front Wall thickness for the storage of the ball are the basic features of the tip according to the invention. This is essentially achieved by cold working and not by machining.

The number of indentations 6 as a support, which form the seat S for the ball 5, is advantageously 3, 4 or 5, and this depends on the size of the ball diameter. If, for example, the ball diameter is greater than 0.6 mm, there are five indentations, while if the diameter is less than 0.8 mm, the number of indentations will be limited to four, in the limit case to three.

The tool known as “drilling”, the use of which for cold forming is already known in numerous branches of industry, comprises (FIG. 3) a cylinder jacket 7 with a shank. Within the jacket 7, three rollers 7 'are arranged rotatably about its own axis and parallel to the axis of the cylinder, which in turn press against the deformed wall of the tube A. FIG. 4 shows, with reference to FIG. 2h, on a larger scale how the end region of the front part A 'of the tube is brought to an exact dimension again after the seat S has been carried out. 8 shows a part of an outer roller and 9 shows a concentrically arranged pin which, by means of its tip 9 ′, presses against the region of the indentation 9 ″, which will form the support for the ball. At the same time, this also presses against the cylinder wall 9 "', whereby an extremely precise centering of the ball seat S with respect to the axis of the tube and in particular with respect to the wall 9"', which will enclose the ball, is assured.

In order to realize the annular holder N (FIG. 5), in addition to a pin 10 which is concentric with respect to the axis of the tube and at the same time to the axis of the seat S, an outer “triplet” is provided. Its outer rollers 11 have a groove 12 for bending the annular edge inwards, by as small a radial dimension as possible for insertion, by snapping the ball 5 d. H. by elastic yielding of the edge is required.

The tool shown on a larger scale in FIG. 6 is used to produce the seat S for the ball 5 (FIG. 2g). Here, a tube A axially arranged to the tool can be seen and, in a vertical plane, two coaxially arranged punch units 13. Each unit 13 comprises a hollow body 14 which is tapered at the front and close to the axis of the tool. The additional taper 15 'of a bush 15 presses against the taper 14', which is coaxial with the aforementioned tip 4 and is detachably fastened in the central bore 16. The purpose of the socket 15 is to determine the common position of the units 13 in a plane perpendicular to the axis of the tube A. A stamp 17 with a tapered front part 17 'is axially displaceable in the hollow body 14. The opposite, outer end 17 "of the punch has a larger diameter than the shaft in order to guide it axially and to form a support for the prestressed cylindrical spring. The outer end 17" also acts as a tappet and is acted upon by the conical surface 19. The conical surface 19 belongs to the inner wall of a bushing 20 which can be moved coaxially with respect to the axis of the tip to be machined.

The conical end regions 21 'of two screws 21 act on the units 13. These are arranged parallel to the axis of the tool and are intended to align the corresponding axes of the units 13 so that they intersect with the axis of the tool.

During the manufacture of the indentations, and as a result of the displacement of the bushing 20, a calibration plunger 22 penetrates into the Tube. The depth of the indentations S and the displacement path of the plunger 22 are limited by the corresponding displacements Z and Z ′ carried out by the body C and by the bushing 20. The pressure force K is exerted on the body C; the body C and the sleeve 20 are in turn biased by the springs 23 and 24.

Claims (9)

1. A point für a ball pen which is fed with liquid ink and comprises a porous wad (2) which feeds to the ball (5) the ink via a likewise porous needle-like part 3, characterised in that the point is obtained starting from a section of a cylindrical tube made of metal, without cutting machining for forming in coaxial sequence a cylindrical rear end area (A") with widened diameter of a central area (A"') which corresponds essentially to the cross-section of the original tube and of a likewise cylindrical front end area (A') with reduced diameter opposite the central area (A"') in that the needle-like pin (3), is inserted with its end remote from the ball (5) into the wad (2), is mounted with its end (3") lying close to the ball in the central area (A"') of the point and in that the wall of the front end area (A') is shaped for the strengthening of the bearing place of the ball and is reduced in its thickness for the bending inwards of the outermost edge ares before the insertion of the ball into the bearing.

2. A point according to claim 1, characterised in that the insertion of the ball (5) into its bearing place with reduced wall is effected by snapping in of the ball in consequence of elastic yielding of the annular edge area (n) in the outermose area of the point.

3. A point according to claim 1, characterised in that the cylindrical tube from which a start is made for the manufacture of the point is rustproof material and in that the original wall thickness of the tube is about 0.1 mm.

4. A point according to claim 1, characterised in that the distance between the ball (5) and the end (3") of the needle-like part (3) is smaller than ³/₄ of the ball diameter.

5. A point according to claims 1 and 4, characterised in that the front end (3") of the needle-like point (3) which determines the outlet of the ink extends as far as into the seating (S) of the ball (5).

6. A point according to claims 4 and 5, characterised in that the cross-section diameter (d) of the needle-like part (3) is formed as large as possible in relation to the diameter of the ball (5) and that in the point the needle-like part (3) is so arranged that the ink collects between its front surface area (3") and the appertaining ball cap.

7. Method for the manufacture of the point according to claim 3, characterised by the sequence of the following operations:

a) separation of the tube part (A) made of steel advantageously of rust-resisting steel and deburring of the edges of the two front ends (fig. 2a),

b) tapering by rolling of the end area of the front part of the tube (A) for the bearing of the ball (5) whereby in the rear part of the tube a plunger (T) is inserted which is moved as far as the tapering included in the constructions (fig. 2b),

c) reduction by radial rotation and rolling of the previously tapered front part (A') of the tube whereby the longitudinal axis of the front part (A') is secured such that it lies coaxial with the remaining part (A" and A"') of the tube (A) (fig. 2c),

d) widening of the rear part (A") of the tube (A) whereby the inner diameter and the outer diameter of the tube area (A"') lying between the front part (A') and the rear part (A") corresponds at least approximately to the rear part (A") of the tube to an accurate size (fig. 2c),

f) simultaneous inner and outer rolling of the front part (A') of the tube with a tool called »drilling« with reduction of the wall thickness and its lengthening resulting therefrom (fig. 2f and 4),

g) construction of the ball seating (5) with the aid of centrally operating punches with conically formed points whereby the ball seating consists of dents (6) the points of which extend in the direction of the axis of the tube and following equalization of the supporting points for the wall with the aid of a plunger (22) which operates coaxially with the axis of the tube (fig. 2g and fig. 6),

h) to bring the outer end area of the tube in particular the part (A') disposed before the ball seating with the aid of a tool called »drilling« simultaneously from inside and from outside to an accurate size whereby for this working procedure the tap for the calibrating from inside and from outside is centered in relation to the places representing the ball seating (fig. 2g and 4),

i) separation of the end (d) of the front part (A') which in consequence of the previous machinings of the tube has become superfluous (fig. 2i),

k) making the edge area or ring for the later fitting of the ball (fig. 2k)

I) bending of the edge area inwards (fig. 5),

m) insertion of the ball by snapping in due to the presence of the flexible annular bending in the outermost area of the point (not shown in the drawings).

8. Method according to claim 7, characterised in that the outer end area (A') of the point for taking the ball (5) undergoes a strengthening and at the same time a reduction of the original wall thickness whereby these features are attained by cold shaping of the material.

9. Method according to claim 8, characterised in that the strengthening and the reduction of the wall thickness of the outer area (A') of the point are intended for the denting for the purpose of the making of the seating (S) for the ball (5) and the elastic yielding of the annular edge area (N) necessary for the snapping in of the ball.

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