US3234772A

US3234772A - Method for forming nib housings and other small articles

Info

Publication number: US3234772A
Application number: US277393A
Authority: US
Inventors: Fehling Hans Reinhard; Harvey Edward Henry
Original assignee: IRC Ltd
Current assignee: IRC Ltd
Priority date: 1962-05-03
Filing date: 1963-05-01
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15

Description

1966 H. R. FEHLING ETAL 3,234,772

METHOD FOR FORMING NIB HOUSINGS AND OTHER SMALL ARTICLES Filed May 1, 1963 5 Sheets-Sheet 1 INVENTORS. 23mm: a Fig. 3. av

Their ATTORNEYS.

1966 H. R. FEHLlNG ETAL 3,234,772

METHOD FOR FORMING NIB HOUSINGS AND OTHER SMALL ARTICLES Filed May 1, 1963 3 Sheets-Sheet 2 VENTORS. HA REINH D FEHLING 8\ BY ED RD HENRY HARVEY 5M IS- cams Y8.

Feb. 15, 1966 R FEHUNG ETAL 3,234,772

eeeeeeeeeeee t5 United States Patent METHOD FOR FORMING NIB HOUSINGS AND OTHER SMALL ARTICLES Hans Reinhard Fehling, Zug, Switzerland, and Edward Henry Harvey, London, England, assignors to I.R.C. Limited, London, England, a company of Great Britain Filed May 1, 1963, Ser. No. 277,393 Claims priority, application Great Britain, May 3, 1962, 16,958/ 62 9 Claims. (Cl. 72-267) This invention relates to housings for the writing ex tremity or nib of a ball point writing instrument and, more particularly, to a new and improved nib housing and method of making such housings and similar small articles. This application is related to our copending application Serial No. 110,518, filed May 16, 1961 for Nib Housing for Ball Point Writing Instrument.

In general, the nib for a ball point writing instrument comprises a housing having a ball-receiving socket at a forward end adapted to receive a writing ball of approximately one millimeter diameter, an internal ink feed duct leading from the opposite or rearward end of the housing to the interior of the socket, and a plurality of partspherical base seats formed at the rear of the socket to support the ball having ink passages between them which extend from the ink feed duct to an annular cavity surrounding the ball. Forwardly of the annular cavity, an inturned lip provides a part-spherical lateral seat which retains the ball in the socket. In addition, the nib housing usually includes an integral rearwardly directed sleeve to facilitate attachment of the housing to an ink reservoir or to a conduit leading thereto.

Heretofore, the housing for a ball point writing extremity has been formed by machining and punching operations which, because of the very small size of the workpiece and the very close tolerances involved, must be performed by relatively complex and highly accurate equipment. Moreover, the quality of the product made in the conventional manner depends to a great extent upon the skill of the tool setter. In our above-mentioned copending application, a nib housing and a metthod of preparing it are described wherein a billet of ductile material is deformed in a die to provide a unitary housing having the desired structure in a single operation, thereby avoiding the disadvantages of conventional nib housing manufacture.

Frequently, however, it is desirable to provide a unitary housing wherein the material forming the ball socket portion has properties which differ from those of the material forming the rearwardly extending sleeve portion. Where the sleeve portion is to be drawn or swaged on to an ink reservoir tube, for example, it should have a higher ductility than is normally required of the material forming the socket portion. Also, in certain instances, it is desirable to add a small quantity of precious metal to the material forming the socket portion but such metal is either unnecessary or undesirable in the material forming the sleeve portion. In addition, it is also desirable, in some instances, to adjust the relative yield strengths of the socket portion and the sleeve portion to assure optimum formation of the housing structure. Finally, it is sometimes desirable to provide unitary nib housings having a sleeve portion of greater length than is normally possible as a result of deformation of a single billet, in the manner described above.

Accordingly, it is an object of the present invention to provide a new and improved nib housing or other small article and a method of making it which provides the above-mentioned advantages not obtainable in conventional housings and methods of making them.

ice

Another object is to provide a new and improved nib housing of integral structure, wherein the socket portion has properties differing from those of the sleeve portion.

A further object is to provide an integral nib housing, wherein the socket portion contains a different material than the material forming the remainder of the housing.

An additional object of the invention is to provide an integral nib housing produced by billet deformation wherein the sleeve portion has substantially greater length.

Another object is to provide a method for making a substantially complete nib housing or other small article of the above character in a single forming operation.

These and other objects of the invention are attained by arranging two billets of suitable ductile material in longitudinal series relation between two die elements defining the exterior and interior shape of the article, and deforming the two billets under pressure applied longitudinally so that, during the deforming operation, they are joined together and deformed so as to conform to the shape of the dies. In the manufacture of nib housings, one die element defines the exterior of the housing and the interior of the ball-receiving socket thereof and the other die element comprises a punch and the billets are deformed by driving the punch into the first die element so that the material of at least the rearward billet is extruded around the punch to form a housing sleeve portion, thereby permitting the housing sleeve portion to comprise a larger volume of material than is the case in housings formed from a single billet of material. In the deforming operation, the two billets may be united either mechanically or by a type of welding action, and by utilizing a forward billet of material selected according to the desired characteristics of the corresponding portion of the article and a rearward billet material providing the desired characteristics for the other portion of the article, an integral article having different characteristics in two different portions is provided. Moreover, the yield strengths of the materials of which the billets are made may also be selected according to the relative ease of billet deformation required of the two portions in order to assure optimum formation of all parts of the article structure and the relative masses of the two billets may be selected according to the relative volume of the two portions to which the desired characteristics are to be imparted. In one embodiment, two spherical billets of differing diameter are utilized while, in another embodiment, one of the billets may be spherical and the other frusto-conical in shape.

Further objects and advantages of the invention will be apparent from a reading of the following description in conjunction with the accompanying drawings in which:

FIGS. 1, 2 and 3 are cross-sectional views illustrating, respectively, successive stages in the billet deformation process to produce a nib housing according to one embodiment of the invention;

FIGS. 4 and 5 are similar views showing successive stages in the nib housing deformation process according to another embodiment of the invention; and

FIGS. 6 and 7 illustrate an embodiment of the process as utilized to form a silver tipped electrical contact, while FIG. 8 shows the completed contact.

In the representative embodiment of the invention shown in FIGS. 1-3, a die member 10 for forming a nib housing comprises a funnel-shaped entry portion 11 leading to a substantially parallel part 12 (having a slight draw) which, in turn, leads to a tapered end portion 13. A socket forming core pin 14, being smaller than the small end of the die cavity, protrudes into the latter from a block 15, an air vent 16 being provided between the block 15 and the die 10 leading from the small end of the die cavity. A

or punch 17, shown in FIGS. 2 and 3, of stepped cylindrical form having a leading end 18 of reduced diameter terminating in a flat end face 19 is arranged to be driven by suitable means (not shown) longitudinally into the die cavity toward the core pin 14. For the specific dimensions and further particulars of the tools in one example, according to the invention, reference is hereby made to the embodiment described in connection with FIG. 18 of the above-mentioned copending application.

In carrying out the process, as illustrated in FIGS. l-3, two

spherical billets

20 and 21 of suitable ductile material or materials are loaded into the die 10. The forward billet 20 is preferably smaller than the rearward billet and rests in the tapered part 13. The billet 20 should be sufiiciently large not to rest on the tip of the core pin 14. Otherwise, it would not be truly centralized by the part 13. The larger rearmost billet 21 rests in the small end of the entry funnel 11 and, it will be observed that there may be a small space between the two billets, as shown in FIG. 1. The punch 17 is applied in a single impact operation, preferably with an impact of defined total energy and velocity, such as 3 foot pounds at at least five feet per second, and the flat end face 19 of the punch first engages the billet 21 and forces the latter into the part 12 of the die and then into contact with the billet 20. In this regard, the rate at which the deforming energy is applied to the billets should be great enough to raise the temperature of the billets to a value at which the yield strength of the material is sufficiently reduced to assure complete plastic deformation thereof.

Upon impact, the material of the billet 20 is caused to intrude into the tapered portion 13 of the die and the material of the billet 21 is caused to extrude rearwardly around the punch, as an exterior sleeve 22. During this deformation, the material of the billet 20 is, in effect, wrapped over the core pin 14 without rupture of its surface layer by reason of its plastic deformation and the escape gap between the shoulder 23 of the punch and the part 12 of the die cavity is sufficiently narrow as to impose such a resistance to the rearward extrusion of the sleeve 22 through the gap that the pressure developed in the die cavity is adequate to ensure that the narrow rim of the cup of the ball socket is fully formed around the core pin 14. It will be noted that the draw of the part 12 causes this gap to diminish in width as the punch 17 advances with the result that the free end of the sleeve 22 is somewhat thicker than its root and may, indeed, be of somewhat bulbous form, as shown in FIGS. 2 and 3.

The

billets

20 and 21 may be made of the same ductile material as one another or of different ductile material. As indicated in the above-mentioned copending application, suitable materials are those possessing sufficient ductility without exhibiting an excessively high yield strength. A particularly suitable material is electrolytic copper but other metals, such as pure aluminum, zinc, silver, gold, lead, ductile brass and certain tin alloys are also suitable.

Typically, the spherical billet 21 is approximately 40 percent greater in diameter than the smaller billet 20 and, in one example, the billet 21 comprised an electrolytic copper sphere weighing 0.156 gram, and the billet 20 comprised a 0.058 gram sphere of the same material. To impart different properties to the socket portion and the nib portion, however, the two billets are made of differing materials having the corresponding properties. In addition, it is usually preferable for the material of the forward billet 20, which forms the socket portion of the housing, to possess a yield strength equal to or less than that of the rear billet 21, which forms the sleeve portion. This relation assures that the forwardly directed pressure applied by the punch 17 through the rear billet 21 will be sufficient to cause the forward billet 20 to be completely deformed so as to conform accurately to the shape of the die and the socket forming core pin 14, the pressure being maintained on the forward billet during deformation by the greater yield strength of the rearward billet which encloses it in the die. Moreover, this also makes it possible to produce a nib housing having a very thin rim surrounding the forward end of the ball socket.

For further details of the deformation process, reference is hereby made to the aforesaid copending application, the disclosure of which is incorporated herein by reference. It will, however, be noted from FIGS. 2 and 3 of the present application that the material of the rearmost billet 21 is projected into the material of the foremost billet 20 and/ or the material of the latter is extruded rearwardly around the material of the billet 21 during deformation so that the two billets become united and form a unitary housing structure. The joint thus formed between the material of the two billets may be wholly mechanical or wholly of a welded nature or partially mechanical and partially welded.

After the blank thus formed has been removed from the tools, it may be forced, tapered end foremost, through the aperture in a drawing die by the application of a suitable mandrel within the sleeve 22. Thereby, the sleeve 22 is drawn out and elongated and, if desired, is reduced in internal diameter. For example, the mandrel may have a diameter the same as or slightly less than that of the part 18 of the punch 17. If such a mandrel is employed, the step in the interior of the blank which is formed by the shoulder 23 of the punch 17 is eliminated and the interior of the blank is made to be of constant diameter for its entire length. Thereafter, the thin transverse diaphragm of material which separates the socket from the sleeve passageway in the blank, which has been removed from the tools, is eliminated in the manner described in the above-mentioned copending application in order to produce the finished nib housing. In a completed writing instrument, the elongated sleeve 22 may, itself, constitute a short ink reservoir or may constitute a socket into which the end of a tubular ink reservoir is fitted.

In the alternative embodiment of the invention shown in FIGS. 4 and 5, the forward billet 25 is of frusto-conical rather than spherical shape. This arrangement has the advantage that it provides a somewhat better keying or locking together of the two portions of the nib housing. To assure self-centering of the forward billet 25, the taper angle of the peripheral surface thereof is selected to correspond with the taper angle of the forward portion 13 of the die member 10. Also, in the illustrated example, the rear billet 26 is just small enough in diameter to be received in the slightly tapering central die portion 12 with the result that the extruded sleeve portion 27 of a housing made according to this embodiment does not have a bulbous end shape, as illustrated in FIG. 5. In one case, the forward billet 25 was made of electrolytic copper and had a weight of 0.060 gram and the rear billet 26, made of the same material, had a weight of 0.104 gram.

The embodiment illustrated in FIGS. 4 and 5 operates in the same manner as that of FIGS. 1-3 but it will be noted that the forward billet material is extruded rearwardly into the rearward billet and/or the rearward billet material is intruded into the forward billet to a greater extent so as to provide a better joint between the two than is normally obtained with the arrangement of FIGS. 1-3. After deformation of the billets in this manner, the thin diaphragm of material separating the socket from the sleeve passageway is removed to produce the finished nib housing and the sleeve 26 may be drawn out and elongated and, if desired, reduced in internal diameter.

The embodiment of the invention shown in FIGS. 6, 7 and 8 is generally similar to that of FIGS. 1-3 except that a silver-tipped stud-type contact is formed. In this case, a rigid die member 30 is provided with a cavity comprising a funnel-shaped entry portion 31 leading to a substantially parallel part 32 (having a slight draw) and a block 33 providing a small air space 34 between itself and the die member 30 is shaped with a shallow recess 35 which is aligned with the end of the parallel part 32.

To form a silver-tipped stud-type contact, a spherical billet 36 of silver is first inserted int-o the cavity of the die member. This billet has a diameter such that it rests within the part 32 above the bottom of the recess 35 and is centered therein by engagement with the wall of the part 32. A spherical tin-plated copper billet 37 is then inserted in the funnel-shaped portion of the cavity, and the diameter of this billet is large enough so that it is held above the billet 36 and preferably is retained at the bottom of the funnel-shaped part 31, as shown in FIG. 6. A punch 17, of the type described previously in connection with the embodiments of FIGS. 1-5, is then driven longitudinally, preferably by an impact of defined energy and velocity, into the die cavity to deform the two billets plastically and join them together in the manner previously described. As illustrated in FIG. 7, this causes the copper billet to intrude forwardly into the silver billet and/or the silver billet to eXtrude rearwardly around the copper billet so that the tWo are joined into a unitary article 38 and the joint thus formed may be wholly mechanical or wholly of a welded nature or partially mechanical and partially welded. In addition, the copper billet is extruded rearwardly around the punch to form a rearwardly directed sleeve or tube 39 and the tin plating on this billet appears on the inner surface of the finished sleeve.

As illustrated in FIG. 8, the silver-tipped contact, after removal from the die member 30, may be mounted in a correspondingly shaped hole formed in an insulating panel 40 so that the silver-tip 41 projects in the form of a stud from one surface 42 of the panel, and an electrical conductor 43 enters the copper sleeve 39 from the other side of the panel. The conductor may be retained in the sleeve by crimping of the enlarged end portion 44 thereof and/or by soldering.

Although the invention has been defined herein with reference to specific embodiments, many modifications and variations therein will readily occur to those skilled in the art. If desired, for example, instead of utilizing the solid punch illustrated in the drawings herein, a punch having a central axial passageway may be used in the manner described in the above-mentioned copending application. Moreover, it will be readily apparent that the invention is applicable to the formation of other small articles as Well as nib housings. Accordingly, all such variations and modifications are included within the intended scope of the invention as defined by the following claims.

We claim:

1. A method of forming a small article having a central recess comprising placing two billets of suitable ductile material into a generally cup shaped die cavity vented at the bottom and bounded by a surface adapted to form the outside surface of the article and having a central core member rigidily projecting from the bottom of the cup-shaped cavity and having a shape defining the inside surface of the recess, the billets being aligned in the cavity with the central core member, and driving an elongated member which is coaxial with the central core member against one of the billets and toward the bottom of the cup-shaped cavity to cause the two billets to be deformed so as to be joined together and form a unitary structure conforming to the shapes of the die cavity and the member.

2. A method according to claim 1 wherein the elongated member is driven against one of the billets by impact.

3. A method according to claim 1 wherein the elongated member is driven against one of the billets within a surrounding cavity surface of slightly greater dimension than the elongated member, thereby causing said one billet to eXtrude rearwardly and form a sleeve surrounding the elongated member.

4. A method according to claim 3 wherein said one billet is made of a material having selected characteristics which are to be imparted to the extruded sleeve.

5. A method according to claim 1 wherein the elongated member is driven against one of the billets within a surrounding cavity surface of slightly greater dimension than the elongated member so as to produce sufficient pressure on the other of the two billets to cause it to intrude forwardly around the central pin and fill the bottom of the cup-shaped cavity.

6. A method according to claim 5 including the step of inserting as the other of the two billets, a billet made of a material having selected characteristics which are to be imparted to the portion of the article forming the central recess.

7. A method according to claim 1 including the step of inserting two billets which are spherical in shape and have different diameters.

8. A method according to claim 1 including the steps of inserting as said one of the two billets, a billet which is spherical in shape and, as the other of the billets, a billet which is frusto-conical in shape.

9. A method according to claim 1 wherein the small article is a housing for the writing extremity of a ball point writing instrument and the core member comprises a central pin having a shape defining the inside surface of a ball-receiving socket, including the step of driving the elongated member against one of the billets so as to cause the other billet to be deformed about the central pin and form the inside surface of the ball-receiving socket.

References Cited by the Examiner UNITED STATES PATENTS 2,009,449 11/1937 Metzger 207-10.5 2,104,222 1/1938 Decker 20710.5 2,473,371 6/1949 Heath et al 29-15555 2,904,173 9/1959 Braun et al. 2076.1 2,904,873 9/1959 Hild 207-61 2,955,222 10/1960 Beesch 20710.3 2,983,253 5/1961 Henriksen 42.4 3,048,148 8/1962 Sireani 120-42.4

FOREIGN PATENTS 803,015 10/1958 Great Britain. 518,433 3/1955 Italy.

OTHER REFERENCES Pearson and Parkins, The Extrusion of Metals, 2nd Edition, John Wiley and Sons, Inc., New York, 1960, (Chapter X, pages 297318).

CHARLES W. LANHAM, Primary Examiner.

LAWRENCE CHARLES, MICHAEL V. BRINDISI,

Examiners.

Claims

1. A METHOD OF FORMING A SMALL ARTICLE HAVING A CENTRAL RECESS COMPRISING PLACING TWO BILLETS OF SUITABLE DUCTILE MATERIAL INTO A GENERALLY CUP SHAPED DIE CAVITY VENTED AT THE BOTTOM AND BOUNDED BY A SURFACE ADAPTED TO FORM THE OUTSIDE SURFACE OF THE ARTICLE AND HAVING A CENTRAL CORE MEMBER RIGIDLY PROJECTING FROM THE BOTTOM OF THE CUP-SHAPED CAVITY AND HAVING A SHAPE DEFINING THE INSIDE SURFACE OF THE RECESS, THE BILLETS BEING ALIGNED IN THE CAVITY WITH THE CENTRAL CORE MEMBER, AND DRIVING AN ELONGATED MEMBER WHICH IS COAXIAL WITH THE CENTRAL CORE MEMBER AGAINST ONE OF THE BILLETS AND TOWARD THE BOTTOM OF THE CUP-SHAPED CAVITY TO CAUSE THE TWO BILLETS TO BE DEFORMED SO AS TO BE JOINED TOGETHER AND FORM A UNITARY STRUCTURE CONFORMING TO THE SHAPES OF THE DIE CAVITY AND THE MEMBER.