US2969583A

US2969583A - Ball point pen

Info

Publication number: US2969583A
Application number: US759827A
Authority: US
Inventors: Schachter Friedrich
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-09-08
Filing date: 1958-09-08
Publication date: 1961-01-31
Anticipated expiration: 1978-01-31
Also published as: GB873007A; CH375627A

Description

Jan. 31, 1961 F, SCH'ACHTER 2,969,583

BALL POINT PEN Filed Sept. 8, 1958 I 2 Sheets-Sheet 1 INVENTOR. Fla/5021ca /1mm? Jan. 31, 1961 sc c 2,969,583

BALL POINT PEN Filed Sept. 8, 1958 Y 2 Sheets-Sheet 2 INVENTOR. FRIEDRICH jCH ICHIFK A rromvsvs United States PatentO BALL POINT PEN Friedrich Schachter, 7333 W. Harrison St., Forest Park, Ill.

Filed Sept. 8, 1958, Ser. No. 759,827 '7 Claims. (Cl. 29-1484) This invention relates to a writing point construction for ball point pens and to the art of fabricating the same, and has as its general object to provide an improved, long wearing, better-writing point, particularly adapted for writing on surfaces (such as glossy surfaces) which normally cause a 'ball point pen to skip.

One of the objects of my invention is to provide a writing point that will write on all surfaces without embodying the disadvantages of those points which are particularly designed for writing on glossy surfaces.

My investigation of this type of pen in which a special effort has been made to attain continuous writing on smoothsurfaces (and other surfaces tending to cause skipping, such as surfaces having finger prints or other coatings that tend to lubricate the surface or to otherwise destroy or reduce the traction between the ball and the surface) indicates that such pens (which usually utilize a ball with a pitted surface for increased traction) customarily have the following disadvantages:

(a) Increase of ink consumption over the life of the writing unit cartridge;

(b) A gradual change (thickening) in the intensity of the line due to wear and the loading of the pitted'surface with an accumulation of a foreign matter picked up from the writing surface and mixed with the ink, and which eventually tends to starve the ink flow;

(c) A rough feeling (of dragging resistance) transmitted to the fingers of the writer in the writing operation;

(d) The build-up of excessive ink (development of blobs) on the exposed areas of the point assembly;

(e) Slow starting, i.e., failure to produce a line at the beginning of a pen stroke, when the pen is first picked up for use after a short period of non-use;

(f) Splitting of lines during directional change in writing caused by insufficient ink feed at a change of direction of the writing path or by lateral shifting of the ball in its socket.

A principal object of the present invention is to provide a ball point pen especially adapted for continuous writing on all types of surfaces and which in addition will overcome the foregoing disadvantages.

More specifically, the invention contemplates such a pen which will provide consistent writing performance over long periods of use;'will.avoid change in line intensity; will maintain uniform ink consumption; will not form or deposit blobs on the writing surface; will exclude the entry of foreign particles into the ball socket; will avoid clogging arising from the picking up of foreign material from the writing surface; will produce a line of color intensityeven when moved over the'writing surface without any writing pressure applied thereto other than the mere weight of the pen itself; will provide smooth rolling of the ball without any feelingof drag against the paper; and will avoidthe splitting of lines.

Ingeneral, the inventionsolves the problems presented above by reducing internal friction in the point. A primary aspect of the invention in this'connection is to pro vide a ball seat which (a) has an extremely smooth surface, within the range referred to in present day industrial mechanicsas a super-finish and (b) a seat having true geometrical conformity to the contour of the writing ball. On this aspect of the situation, I have observed that in the average ball point assembly (which under common present day practice is formed by impressing the ball into the seat) the seat does not accurately conform to the ball surface, due to spring-back which occurs in the metal of the seat subsequent to the seat forming operation. My experiments have shown that the seat which constitutes the bottom of the ball socket should be wear resistant, highly malleable material, while the lip which constitutes the side walls of the socket should be of a material 7 suitable to firmly position and retain the ball, minimizing the tendency to yield while the seat is being formed, and to provide socket walls resisting expansion under writing pressure.

I am aware that many prior workers and patentees in this art have discussed at length the problem of wear of the ball against its .seat and have proposed many remedies, but so far as I am aware none of them have discovered the particular combination of features by which the problem is solved in the present invention.

The invention further contemplates a method of fabricating an insert seat and a method to achieve control of the geometrical condition of the ball socket.

Other objects and advantages will become apparent in the ensuing specification .and appended drawing in which:

Fig-1 is an axial sectional view, on a magnified scale, of the tip of a ball point pen embodying my invention;

Fig. 2 is a similarly magnified fragmentary axial sectional view, showing astage in the assembly of parts constituting said tip;

Fig. 3 is .a transverse sectional view of the tip taken onthe line 3-3 of Fig. 1; I

Fig. 4 is a fragmentary axial sectional view of a pen tip embodying a modified form of the invention;

Figs. 5-7 illustrate processing steps.

Referring now to the drawings in detail, I have shown in Figs. 1 and 3 thereof,as an example of a preferred form of the invention, a writing point assembly embodying, in general, a barrel tip, generally referred to by the character A; a writing ball B retained in the tip A, and a seat C providing a thrust bearing for the ball B as it rotates during a writing operation.

The socket A includes a base portion 16} having an ink passage bore 11 and having an external wall 12 which may either be cylindrical or frusto conical or double curved, as selected. Extending beyond the base portion '10 is a lip 13 of circular cross section having an internal wall 14 (which may be cylindrical) and having an offset annular supporting shoulder 15 extending from the bore 11 to the internal wall 14. Wall 14 and shoulder 15 cooperatively define an ink well in which ink flowing through the base passage 11 may spread aroundthe ball B preliminary to-being carried by the ball to the writing surface. The shoulder 15 may be frusto conicalas shown, or of any other suitable contour for supporting the seat C.

Beyond the cylindrical wall 14, the' lip 13 has an internal bearing wall 16 formed as an equatorial zone of 'a sphere, and conformed closely to the surface of the in the forming .of the ball seating surface in the seat C i I I (by, pressing the ball B againstthe seat) there will be .no deformation in the lip13 arising from expansion-of.

, seat ,O. under the coining pressure ofthe seat forming ?atented Jan. 31, 1961 Y device (either the ball B or a special tool with a hemispherical end corresponding to the surface of the ball).

In this particular form of the invention, the seat C is of modified torus form, and this form is attained by the deformation of a ring of circular cross sectional wire as will presently be described. The seat comprises a cir- 'cumferentially continuous outer body portion 18 having respective outer annular surfaces conformed generally by the forming pressure) to the shoulder and to the internal wall 14 and an inner portion having a plurality of circumferentially spaced bearing surfaces 19 consisting in zonal segments of a spherical surface conformed to the surface of the ball B and interrupted by a corresponding series of intervening ink passages 20. Although a generally triangular notch form is disclosed, the passages 20 may be of any selected cross section. Also, as shown in Fig. 4, the passages Zita may be disposed on the outer side of seat C, between the same and the internal wall surface 14 and shoulder 15, and the seating face 19.

The ink passage notches may be aligned with the socket axis (comically, as shown in Fig. 1). Alternatively, the passages may be disposed diagonally with respect to respective radii, i.e., tangential to a circumference at or within the radius of ink supply bore 11.

The ball B preferably has a smooth, highly finished surface, although the invention contemplates the possibility of using a ball with a smooth spherical surface pitted by a large number of minute cavities. The material of the ball, as previously indicated, is so related to that of the seat as to provide a readily dissipating characteristic in any alloy that may be formed by welding of molecules of the ball to those of the seat (in the case where both ball and seat are of metal). For example, the ball may be of tungsten carbide with a surface finish of 1 micro inch (R.M.S.) smoothness.

The seat C is of a wear resistant material which, although tough, is extremely soft, i.e. highly malleable, so as to faithfully mirror the coining surface of the ball (or a coining tool) used in shaping the bearing surfaces of the seat. A low coefficient of friction is preferred.

The seat may be a silver alloy such as coin silver (approximately 10% copper and 90% silver) or platinum iridium (approximately 90% platinum and 10% iridium) or tellurium copper /z% tellurium and 99 /2% copper, approximately). Each of these alloys has the characteristic of softness hereinbefore described. As another example of a suitable material, the seat may be an alloy of one of the platinum group metals and the self lubricating substance such as molybdenum disulfide, added thereto in suflicient quantity to provide the low coefiicient of friction. Another material (not wholly metallic) that can be used is a sintered mixture of Teflon (tetrafluoroethylene resin) particles and particles of a suitable metal, or any of the resins in the fluoro-carbon group closely allied to Teflon, such as Kel-F resin; or any equivalent plastic material.

Alternatively, the ball may be of a material such as sapphire or hardened glass or other ceramic substance such as sintered aluminum oxide or sintered glass, or other suitably hard material.

The lip 13 is of considerably harder material than the seat C. For example, the lip (and in fact the entire socket unit A) can be fabricated from free-machining brass or bronze in accordance with conventional practice in this art.

Method of fabricating Referring first to the preferred form of the invention shown in Fig. 1, the method of fabricating this point assembly is shown in part in the related Fig. 2, which illustrates the parts in an intermediate stage of fabrication. The lip 13 will be seen to have a substantially uniform flare out to its end, which has a greater wall thickness than that of the finished tip as shown in Fig. 1. The internal cylindrical wall 14x extends uniformly to the tip. 'Its diameter is such as to barely receive the ball B. The seat Cx is of true toroidal form, and is fabricated from a short length of fine soft wire of one of the soft materials previously indicated, the ends of the length of wire being carefully formed so as to provide, in effect, a closed ring when inserted in the socket. Because of the extreme smallness of the ring, the invention contemplates, as a preferred method, the forming of the ring on an attachment of the ball assembly machine either by straightening and cutting off the proper length from straight wire, forming it around a mandrel, preferably using the mandrel to feed the ring into the socket; or by forming a continuous helical coil from which one turn at a time is severed and fed into the socket to form the seat ring. Alternatively, a true ring can be formed on the end of the tangential stretch of wire, cut off at the 360 point and moved along its axis into the socket, or straight lengths of wire may be cut to the proper length and then formed into rings.

The seat forming operation may include the element of softening the seat by heating the same immediately prior to or simultaneous with the impressing of the ball surface therein.

In fabricating the socket A, I start with a solid block of suitable metal, and shape the exterior thereof. Simultaneously therewith, or thereafter, the internal machining is performed to provide the ink supply bore 11 and the internal wall 14 of the lip 13, as well as the shoulder 15. The seat C is then inserted into the socket (the ink passages formed previously or subsequently) and the ball B is inserted over the seat, to provide the assembly shown in Fig. 2.

In the next step of the process, pressure is applied to the ball through a suitable tool (not shown) to press the ball firmly against the annular ring of wire constituting the seat C in its initial form. Alternatively, a tool with an integral semi-spherical end, may be employed in lieu of using the ball B. The pressure causes the seat ring C to be deformed to the shape illustrated in Fig. l, the bearing surfaces 19. Because of the high ductility of the metal in the seat ring C, there is no appreciable spring-back when the pressure is released.

Either simultaneously with this operation of forming the bearing surfaces in the seat, or either before or after the seating operation, the lip 13 is drawn inwardly to form an equatorial zone encircling the ball.

An important aspect of the invention, in solving the above mentioned problems, is that of providing improved concentricity between the internal and external walls of the socket, thereby providing improved uniformity in the wall structure and its yielding to the forming actionin which the socket is formed around the ball.

Figs. 5 and 6 illustrate a seat-forming operation in which a straight length of soft wire 30 is fed as indicated by the arrow thereon into a gap between a movable female die 31 to a point where it is arrested against a stop 32 which constitutes one of a pair of

guides

32 and 33 in which the die 31 is slidably mounted. Then the die 31 is advanced transversely of wire 30 as indicated by its arrow, shearing a short length 30' from the end of wire 30 as indicated at 34 and wrapping this short length 36' around a fixed mandrel 36 projecting at right angles to the plane of die 31 to form the seat ring C, the wrapping movement being completed by a pair of curling jaws 37 moving together on a line tangent to the periphery of the formed seat ring C along the path indicated by their respective arrows. The ring C is then ejected from the mandrel 36 in a direction parallel to the axis thereof by an ejection sleeve 38 seen in Figs. 5 and 9. A socket A, presented to the mandrel 36 in coaxial relation thereto, receives the completed ring C as an insert, as shown in Fig. 7, and continued movement of sleeve 38 may be utilized to move the assembly of ring C and socket A ofi the mandrel 36 (and if desired at the same time the end of sleeve 38 may impress the ink passages 20 into the ring C).

I claim:

1. A method of fabricating a thrust bearing for a writing ball comprised of a socket, said socket having a ball receiving bore, an annular shoulder projecting inwardly from the base of said bore, an annular lip surrounding and defining said bore, and means for conducting ink from a reservoir to said bore, and an inserted ring having a face permanently conforming to the contour of the ball, which ring is of uniform cross section and is deformable without appreciable spring back, said method including the following steps: fashioning said socket of suflicient bulk and from material of suflicient strength to retain its original dimensions when the socket is supporting said ring in an operation of forming the ring; fashioning from a length of malleable wire of material having no appreciable spring back, a split ring, said wire being softer than the material of the socket and the ball, said length of wire being such as to provide a substantially closed ring having a diameter corresponding to said bore; inserting the ring into the bore; applying a substantially unyielding spherical surface against the face of the ring to deform the ring to form a thrust bearing surface concentric with said bore having true geometric conformity equivalent to the contour of the writing ball and simultaneously forcing the ring to conform circumferentially to the walls and shoulder at the base of said bore, but the deforming being limited to an amount that no appreciable spring back is developed due to the forming operation, the annular shoulder being of such size as to support and hold the ring in position and to oppose the forces applied to the face of the ring both during and after the deformation.

2. The method as set forth in claim 1, wherein the deforming pressure applied against the ring is limited so as to provide an annular ink well of substantial extent in said socket between the exposed contour of the bearing ring and the intersection of the ball and the socket wall.

' 3. A method as set forth in claim 1 wherein the surface of the ball seat has a smooth finish within the range referred to in present day industrial mechanics as a super finish.

4. The method defined in claim 1, wherein said wire has circular cross section.

5. The method defined in claim 1, wherein the wire is fed in a continuous length to an apparatus cutting off an exact length, forming a ring and injecting the same into the bore of said socket.

6. The method defined in claim 1, including the additional step of providing said ring with a plurality of ink channels to assure a uniform flow of ink from said reservoir to said writing ball.

7. The method defined in claim 1, wherein the wire ends are cut at angles providing substantially parallel faces when the ring is closed.

References Cited in the file of this patent UNITED STATES PATENTS 2,267,229 Zimmerman et al Dec. 23, 1941 2,718,051 Cloutier Sept. 20, 1955 2,834,321 Dufresne May 13, 1958 2,847,975 Lawton Aug. 19, 1958 2,855,665 Alldredge Oct. 14, 1958 FOREIGN PATENTS 945,809 France Dec. 6, 1948 1,108,400 France Aug. 31, 1955 935,473 France Jan. 16, 1956 (Addition to No. 66,051)