US2847751A - Method of making a ball for ball point pen - Google Patents

Description

United States Patent O METHOD OF MAKING BALL POINT PEN Application June 13, 1955, Serial N0. 515,120 7 Claims. (Cl. 29148.4)

A BALL FR The present inVention relates generally to ball point pens, and more particularly 120 an improved method of making a ball for ball point pens which enables the peu to write n glazed, oiled, er similar surfaces having relatively low coefiicients of friction.

For many years, until comparatively recently, the difficulty of writing with free-flowing liquid ink upon highly glazed er oiled surfaces was widely recognized as an inherent shortcoming in the writing implement art. A long forward step was made With the ddveloprnent cf quick-drying inks having W surface tension and high adsorptive qualities. The use of such inks in split point pens has generally surrnounted the fundamental difliculty above noted. In other words, with inks now available, it is only necessary to spread the ink in a satisfactory manner over glazed paper or the like in order to obtain the desired result.

Considering ball point pens, however, the ability to spread ink over a glazed or oiled surface involves more than the employment of a particular type of ink. As is well known, the ink from ball point pens is applied to the paper by rolling a spherical ball over the paper, the ball being coated with a film of ink. Thus, there exists a theoretically nonsliding printing engagement between the ball and the paper, as distinguished from the familiar sliding or brushing engagement of a split pen point. From its inception, the ball point peu has been notoriously inefficient in use With glazed paper notwithstanding the employrnent of inks having high adsorption. The reason for this, of course, is that the ball at the tip of theball point peu tends to slide, rather than to roll, on the glazed surface, the friction between the paper and the ball being insufiicient to cause the latter to turn in its socket.

lt has now been found that by providing a ball having an especially prepared roughened spherical surface, a coeflicient of friction is obtained which is suflicient to enforce rolling contact of the ball even on glazed surfaces. I1: has also been found that a particular geueral type of abraded surface is distinctly preferable frorn the stand point of the operative life of the tip which retains the ball. The present invention, therefore, teaches a method for roughening the surface of a ball for a ball point pen.

lt is a primary object of the invention to provide a method of making a roughened ball for a ball point pen which operates efiiciently with glazed, oiled or other smooth ink-receiving surfaces.

It is another object of the invention to provide a ball fr ball point pens which has its spherical surface provided with an especially roughened finish for increased coefiicient of friction With smooth surfaces.

It is another object of the invention to teach a method for providing a roughened finish on a ball for ball point pens.

The foregoing, along with additional objects and advantages, will be apparent from the following description taken in conjunction with the accompanying drawing, in which:

Figure 1 is a fragmentary cross-sectional view taken on the longitudinal axis of a filler for ball point pens, the

filler including a tip assembly having a ball constructed in accordance with the tea-chings of the present invention;

Figure 2 is an enlarged representation of a ball similiar to that of Figure 1, prior to being completely forrned;

Figure 3 is an exaggerated cross-sectional representation of a ball similar to that of Figure 2 after an abrading operation; and

Figure 4 is an exaggerated cross-sectional representation of a ball similar to that of Figure 3 after a burnishing o1 polishing operation.

Referring more particularly to the drawing through the use cf reference characters placed thereon, the numeral 10 designates generally a filler for a ball point peu. As is clear from Figure 1, the filler 10 eomprises a tip 12 press-fitted into one end of a reservoir tube 14 and provided with a socket 16 for accomrnodating a spherical ball 18.

The tip 12 has a main longitudinal assage 20 for comducting ink frorn the reservoir 14 down to the socket 16.

-A plurality of grooves 22 is provided for insuring dis tribution of the ink over the interior of the socket 16. As will be observed from Figure 1, the interior dimension or spherical radius of the socket 16 rnay be somewhat greater than the spherical radius of the ball 18, which leaves a gap or space 24 between the surface of the ball 18 and the surface of the socket 16, and thus provides a shell-like passage into which ink may emerge from the lower end of the passage 20 and grooves 22. Such a film of ink between the socket 16 and. the ball 18 eliminates actual surface engagernent between these elements, and thus serves as a liquid lubricant. The extreme lower end of the socket 16 is fonned by an annular edge 26 which, as is well understood in the art, is spun inwardly so as to retain the ball 18 within the socket.

Figure 2 depicts a ball 28 having a smooth polished spherical surface 30, as is conventional in respect to balls used for ball point pens. This type of ball, used in ball point pens since their inception, has perforrned with general satisfaction except when used upon glazed 01 oiled surfaces. In these latter instances, the coefiicient of fri-ction between the smooth surface 30 of the ball 28 and the particular glazed or oily surface has been insufficient to cause the ball to rotate in a manner to deposit ink on such surfaces.

The illustration -of Figure 3 shows a ball 32 provided with a roughened surface 34 forrned by lapping the srnooth spherical surface 30 of a ball 28 with an abrasive dust. A satisfactory abraded surface 34 has been obtained with the use of flowered corundum powder 0f approximately 700 mesh in an oil vehicle. The lapping operation may comprise rolling the ball between two hard surfaces charged with the abrasive substance.

It may be mentioned at this point that a ball 32 provided with an abraded surface 34 could be employed in the tip 12, and Would perforrn witn fair efliciency upon smooth glazed ink-receiving -surfaces. Experience has demonstrated, however, that the surface 34 has minute radial projections which penetrate the lubricating film of ink and rasp the interior surface of the socket 16 to an extent that the latter quickly becomes worn to such an extent that the ball 18 rnay be completely received in the socket 16. Obviously, under such a condition, the filler 10 ceases to operate.

Figure 4 illstrates a ball 36 provided with an indented surface 38, wherein the rasping points of a surface 34 have been eliminated by means 0f a burnishing or polish- Ing operation. A satisfactory burnishing operation comrasping points are, at the most, only slightly altered in such a burnishing operation, and remain as indentations in the common spherical surface. Alternatively, the rasping points may be removed, or at least flattened sufficiently to avoid the deleterious wearing action abo ve note d, by a final light p01ishing o1 l-apping operatiqn employing an abrasive which is substantially finer than that used in the abrading Operation.

It i-s' recognized, incidentally, that the prior art includes examples of ba1ls having other than smooth, C011- tinuous spherica1 surfaces, but the surface diseonti nuities therein are produced by incision or, in some c-ases, by molding. It is not deemed possible, however, to obtain either the necessary close conforrnance to overa'1l sphericity of the bal1 01' the equally necessary fineness of abraded surface where these 1atter forming methods are used. In general, a pitted or indented surfaee is preferab1e over one which contains a pattern of directionally continuous 1ines.

It is to be understood that the use of the expression indented surface is not meant to be limiting, but to be descriptive of a s'urface generally simi1ar to that obtainable in the abrading and burnishing process described hereinbefore. In other words, an indented surface as used here implies a surface having a multiplicity of mieroscopic abrasions of unpatterned direction, and especially such a surface wherein abradent projections have been removed, as by burnishing. Such =a snrface might, for example, be described as having a satin finis it is not, 011 the other band, produeible by ordinary molding or by incision tooling, which involves specific rernoval of appreciable amounts of meta1.

][t is not meant to imp1y that the abovedescribed process is the only way in which a satisfactorily roughened surface may be obtained. F01 example, a surface sorroded by chemicals, as in etching, could be considered equiva1ent to the mechanically abraded surface described above, provided on1y that the same requirements for overall sph-ericity, fineness of surface texture, and absence of rasping peaks be met. Various tools, abrasives, etc. may be used in mechanical abrasion of the spherical surface and in subsequent burnishing of the same.

In use, it is evident frorn the foregoing description that a ball 36 provided With an indented surface 38 is mounted in the socket 16 of a tip 12, as is the ba1l 18 of Figure 1. The coefficient of friction between such a ba'1l and even very smooth surfaces, such as glazed or oihd paper, is sufl1cient to cause the ball to rotate in its socket as the tip is moved over the papex'. As a result, a eontinuous path of ink is transferred from the ba1l to the paper surface as is well understo od in the art.

Clearly, there has been provided a ball for ball point pens and a method for providing a roughened finish on the same Which together fulfi1l the objects and advantages sought therefor.

It is to be understood that the foregoing description and the accompanying drawing have been given only by way of illustration and exarnple. Neither is it to be coustrued in a limiting sense, and the scope of the invention is to be considered limited on1y by the clairns which follow.

What is c1aimed is:

1. In a method of producing a bal1 for a ba1l point peu, the steps of finishing the ball to an intermediate smooth g1ossyspherical surface, roughening said surface to provide a multip1icity of crater-1ike indentations and peak-1ike proiections, and subsequently flattening the tops of said peak-like projections to provide a cratered substantially spherical surface 011 said ball.

2. The method of claim 1 wherein said roughening step comprises subjecting said surface to the action of a corrosive chemieal.

3. The method of cla-im 1 wherein said roughening step compr ises subjecting said surface to mechanical abras1on.

4. T he method of clairn 1 wherein the step 0f flattening the tops of said peak-like projections is accomplished by a burnishing operation.

5. The method cf c1aim 4 wherein said burnishing operation cornprises rolling the ball between hard, polished surfaces.

6. The method of c1airn 1 wherein the step of flattern ing the tops of said peak-like projections is accomplished by a light polishing operation.

7. The method of claim 6 wherein said polishing operation comprises abrading top portions of said peaks with a relatively fine abrasive materia1.

References- Cited in the file of this patent UNITED STATES PATENTS 1,240398 Wood Sept. 18, 1917 1527971 Forsell et a1 Mar. 3 1925 1799034 Althoff Mar. 31, 1931 2532655 Backer Dec. 5, 1950 2,53612 4 Bolvin et a1. Jan. 2, 1951 2,548264 Howe Apr. 10, 1951 FOREIGN PATENTS 894,857 France Mar. 20, 1944 250,923 Switzerland Dec. 1, 1947 1009193 France Mar. 5, 1952

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