US2976610A - Method of forming ball point pens - Google Patents

Description

March 28, 1961 A. G. scHucK Filed July 31. 1953 March 28, 1961 A. G. SCHUCK 2,976,610

METHOD OF FORMING BALL POINT PENS Filed July 51. 1953 2 Sheets-Sheet 2 IN VEN TOR. Jun 01w 6. 621/006 24 BY 15 L- y W m j 0411 I235 METHOD OF FORMING BALL POINT PENS Anthony G. Schuck, Alhambra, Calif., assignor, by mesne assignments, to John M. Lee, Los Angeles, Calif.

Filed July 31, 1953, Ser. No. 371,650

3 Claims. (Cl. 29-441) My invention relates generally to ball point writing instruments, and more particularly to a method for forming precision ball points.

The'major problem of the ball pen industry is improvement and control of the writing qualities of ball point assemblies. Through extensive research and the enormous production of recent years, optimum characteristics for the internal and external design of the points have become well known. However, it has been impossible to maintain close production control over the writing quality of the points while achieving the high rate of output that is economically necessary.

In choosing to illustrate the principles of my invention, 1 will refer to a type of point construction which has become conventional for use in modern ball point pens. it should be understood that I do not intend to thereby limit the invention to a particular point construction, as the latter may be modified and improved from time to time while still advantageously using the method and apparatus set forth herein.

Considering a greatly enlarged section of a point assembly as shown in the drawings, the nose of the point is formed with an internal socket in which is seated a spherical ball. When writing, pressure is applied, the ball rotates or rolls to pick up ink from an internal reservoir and carries it forwardly or outwardly for transfer to the writing paper. To restrain inward movement of the ball, a bottom section of the socket forms a frictionless seat against which the ball is free turning. This seat portion of the socket is usually separated from the side wall portions of the socket.

To hold the ball in place within the point, the wall of the nose is extended forwardly beyond a transverse plane passed through the center of the ball and folded inwardly to form a retaining ring portion. The central plane through the ball may be referred to as the equator of the ball, and the portion of the nose wall extending forwardly beyond the equator as the point rim. Normally, the rim has a frusto conical surface tapered inwardly toward the axis of the point, and terminated by a thin inturned edge whichlies immediately adjacent the ball. In order to distinguish between the two portions of the rim, I will herein refer to the angled frusto conical surface of the rim as the rim angle, and the terminal surface of the rim as the rim edge or lip.

The internal side wall surface of the rim forms with the adjacent central portion of the ball, a metering or orifice section to control the rate of ink flow as determined by the clearance between the two members. As can be appreciated, the control of this clearance is critical in obtainin a pen point having uniformly good writing qualities. In addition to the control of clearances, it is essential that the shape and surface smoothness of the various working portions of the point he precision formed to close tolerances. I

With the foregoing in inind, it is therefore a major object ofmy-invention to provide a method for forming ball pen points of superior and uniform quality.

ir d States .2 1

An equally important object of the invention is to provide a method for forming ball pen points at a high production rate without hand finishing operations.

It is another object of my invention to provide a method for coining or swedging the ball against 'the bottom of the socket and folding the rim against the ball in a two step operation, to form an improved ball seat and a correct rim angle for avoiding rim dents in further operations.

These and other objects and advantages of the invention will become apparent from the following detailed description of the method and a preferred embodiment of the apparatus, and from an inspection of the accompanying drawings in which:

Fig. 1 is a longitudinal section through a swedging apparatus for forming the ball seat and the point rim;

Fig. 2 is a diagrammatic plan view of the operating stations on a worktable;

Fig. 3 is an enlarged partial section through the first swedge and the tip of the pen point;

Fig. 4 is a greatly enlarged section taken in the area of the circle 4 of Fig. 3;

Fig. 5 is a view similar to Fig. 3 showing the second rim angle swedge in position;

Fig. 6 is a longitudinal section through a spinning apparatus for expanding the rim material;

Fig. 7 is a cross section taken along the line 7-7 of Fig. 6;

Fig. 8 is an inverted perspective view of the spinning roller head;

Fig. 9 is a bottom plan view of the spinning roller head;

Fig. 10 is a schematic view showing the relationship of a pair of spinning rollers to the pen point;

Fig. 11 is a diagrammatic view taken in the direction of the arrow 10 of Fig. 6; and

Fig. 12 is an enlarged section through the tip of the pen point.

Referring now to the drawings and particularly to Figs. 1 and 3 thereof, the numeral 15 designates generally a ball pen tip or point assembly comprising a tubular body or shell 16 rotatably supporting a forward writing ball 17. Body 16 has an internal bore 18 therein leading forwardly to a socket 19 in which ball 17 is mounted, and serves to supply ink to the back face of the ball. After completion, point 15 is attached to an elongated ink reservoir or cartridge opening into bore 18 and is ready for use in a pen.

Point body 16 is initially machined to shape by conventional methods with the side walls of socket 19 opened so that ball 17 may be fitted freely therein. As is indicated in the. diagrammatic view of Fig. 2, the machined point body 16 may be mounted on a rotatable work table 20 for finishing operations. Table 20 has a plurality of work stations 21 spaced circiunferentially and adapted to hold a point body 16 in upstanding position. As table Ztl is indexed, stations 21 are brought in alignment under different working heads for performing sequential finishing operations.

In general, the manufacturing of a point requires three steps. First, the ball 17 is dropped or inserted into socket 19. This is done by conventional mechanisms and forms no part of my invention. Secondly, die means are employed to seat ball 17 against the bottom of socket 19 and fold the side walls of the socket inwardly over the equator of the ball. The folded side wall portions of socket 19 form a rim surface 24 which is of forwardly tapering frusto conical shape and is terminated by a thin annular lip or edge 25. Ball 17 is engaged downwardly against a spherical beveled surface 26 surrounding the top of bore 18. Following these swedging steps, the rim is subjected to a rolling operation with roller means bearing against the outer or rim angle surface 24 to iron out the material lying between the rim angle and ball 17, causing the material to expand. This expansion creates a clearance between ball 17 and the inner wall of rim 24 to define a metering section 28 in the region above the equator of the ball to control the rate of ink flow.

, In Fig. 1, I have illustrated a simplified form of swedging apparatus which is capable of carrying out the swedging or coining operations as will now be considered in more detail. Typically, fixed frame member 30 supports a vertically reciprooab'le spindle 32 which is moved up and down by means of an upper collar 33 that is connected to a reciprocating mechanism (not shown). Spindle 32 is held against rotation within frame 30 by vertical keys 33 which slide in grooves formed in the frame.

Mounted at the bottom end of spindle 37 is a female swedging die 36 having a central upwardly open working surface 37 of generally conical shape. The axis of surface 37 lies along the axis of spindle 31, and die 36 is held fixedly to the spindle by a lower locking cap 38 which is flanged outwardly and threadedly engaged to the spindle.

Spindle 32 is positioned in vertical alignment with one of the work stations 21 on table 20 so as to extend coaxially with the longitudinal axis of the upstanding pen point 15. As spindle 32 is moved downwardly against point 15, working surface 37 bears downwardly against the point with a gradually increasing pressure. Die 36 is the first of two dies used in the swedging operation, and its exact shape and relationship to point 15 must be considered in detail.

Referring to Fig. 3, it will be seen that a lower section 40 of working surface 37 is offset slightly from the upper section and is adapted to bear against the angular surface of rim 24. An adjacent upper section 41 of surface 37 is spaced inwardly by a step or shoulder 42 and is of frusto spherical shape so as to seat solidly against the surface of ball 17. Shoulder 4-2 is formed with a small radius corner so as to have a downwardly and inwardly directed sectional profile. It should also be noted that die surface 40 and the rim angle 24 formed thereby, lie at a relatively more obtuse angle with the axis of point 15 than in the finished point shown in Fig. 4.

First swedging die 36 has two functions; that of pressing ball 17 downwardly to form seat 26, and that of partially folding the rim angle 24 and lip 25 inwardly. As die 36 descends the initial pressure is applied to ball 17 so as to form seat 26. At this time, substantially all of the pressure is applied to ball 17 and seat 26 .is swedged or coined into a very smooth surface with all initial burrs or flaws being removed.

A light and gradually increasing pressure is applied to rim angle 24 so that it folds inwardly to conform to the die surface 40 as die 36 continues to descend. During this time, the arcuate shoulder 42 bears downwardly against rim lip 25 so as to form a rounded semi-circular or crowned surface which provides a small annular corner or pocket bet-ween the rim lip and the adjacent surface of ball 17. The purpose of this inner angle or radius is to smooth out such irregularities in the lip as may remain after machining operations. Although such burrs may be microscopic in nature, they tend to interfere with a smooth flow of ink from the point, and form jagged or rough edges which pick up lint as the writing ball travels over the surface of the writing paper.

Another feature of the radiused type step die 36 is that it performs lip 25 into such a shape as to have less tendency to wrinkle or break when the subsequent rolling or spinning operation is carried out. The elimination of sharp corners upon rim lip 25 permits a greater degree of distortion without wrinkling or rupture. 'Dhe principle of this may be explained by considering the greater difficulty involved in bending a square sectioned bar I the surface of ball 17.

4 without edge wrinkling, than in bending a bar of round section. a

In prior finishing operations, it has been considered sufiicient to seat ball 17 in' the manner described, and to form an obtuse rim angle 24 by swedging with a single die which was of sutficiently fiat angle to perform both functions. The point 15 was then moved directly into a spinning or rolling operation where the rim angle 24 was made more acute by the action of spinning rollers. This prior method has not been satisfactory, and two major defects are found in points so produced. Because the pressure is divided between ball 17 and rim angle 24, the internal wall surface of the rim in the metering section has not been worked sufficiently to smooth out any machining flaws which might remain. Also, when rollers are used to change the shape of rlrn angle 24 a sharp hump or corner is initially presented to the rollers and the impact of the rollers against the rim often produces rim dents which cannot be smoothed out.

To overcome these difficulties, I have introduced a second swedging operation which takes place before the rolling or spinning operation. For this step, I use a second female swedging die 44 which is seen in Fig. 5. Die 44 is adapted to be supported in the type of apparatus as shown in Fig. 1 for reciprocating movement. The bottom of die 44 is formed with an upwardly open conical working surface 45 which is of simple, straight walled shape, and is at an acute angle with the axis of point 15 corresponding exactly with the inclination of the rim angle 24 desired for the finished point. Because of its acute angle, surface 45 passes above and does not engage with Thus, as downward pressure is applied, surface 45 transmits its entire impact value to rim angle 24 and is able to smooth out the interior wall surface of the rim withoutany damping action as would occur if part of the pressure were transmitted to the ball.

In changing the shape of rim angle 24, die surface 45 acts simultaneously against the-entire circumferential area of the rim angle. This action does not apply pressure at a single area of contact as in the case of a roller, sci that there is no possibility of a localized deformation or dent. When rim angle'24 is completely formed by the action of surface '45, it has the exact angle of inclination of the finished point. Therefore, the subsequent action of spinning rollers has much less tendency to cause rim dents.

The remaining operations, performed upon point 15 is illustrated in Figs. 6 to 11, and is primarily concerned with producing the correct clearance between ball 17 and the wall of rim angle 24 in the metering section 28. Some prior methods of spinning or rolling the point have applied pressure to both the rim wall and the ball in an attempt to control the clearance developed by the rolling action. However, these methods divide the pressure between the ball and rim so that in order to work the rim properly it is necessary to apply considerable pressure to the surface of the writing ball. In applying such pressure to the ball there is a strong possibility that the highly finished surface of the ball will be marred so that erratic writing qualities may develop. This is particularly true in the case of writing balls made of relatively soft stainless steel such as are used with acid-type quick drying inks to avoid corrosion.

The principle of rim expansion used to develop the clearance in the metering section of the point is that pressure applied against the rim angle causes a gradual decrease in the thickness of the rim wall. Since the same volume of material is present in the rim before and after rolling, the result is that the rim must expand circumferentially and thereby develop clearance with the adjacent portion of the ball surface in the metering section of the point. This determines the flow rate of ink from the point and hence the line shading of the writing.

While the application of pressure to both the rim and the ball has the disadvantages above stated, there have also been found to be serious difficulties with the applicaaorta-ere tion of pressure solely to the rim wall of the point using prior rolling methods and apparatus. The principle objection found in prior rolling means used against the rim alone has been that the rim lip becomes distorted and broken down into an irregular shape before sufficient rim expansion has taken place. Such an irregular rim lip surface tends to accumulateink, and to gouge into the Writing paper and collect lint which soaks up even more ink and smears the Writing paper from time to time.

To overcome these objections, I provide rolling means which tend to ride up the surface of the rim angle as well as circumferentially around it. This prevents the flow of material along the rim angle toward the rim lip so that the latter is left in the smooth and regular shape formed during the swedging operation. Enough pressure can be applied to cause the desired amount of rim expansion without any breakdown of the rim lip.

Referring now to Fig. 6, a simplified form of apparatus for performing the rolling operationis shown. It is to be understood that the structure for reciprocating and rotating the spinning or rolling head may be refined considerably without changing the principles of my invention. Typically, a frame member 50 rotatably supports a sleeve 51 by means of ball bearings 52. Mounted for vertical reciprocating movement within sleeve 51 is a driving spindle 53 which is moved up and down by a collar 54 adapted to be connected to a reciprocating mechanism (not shown). Spindle 53 is keyed for rotation with sleeve 51 and the latter is formed with a pulley 55 thereon adapted to be engaged with a belt 56 for rotational drive.

At the bottom of spindle 53 is a mounting head 58 on which are positioned a plurality of circularly spaced rollers 59. Pen point 15 is held in work table 20 and is brought beneath head 58 so that the longitudinal axis of the point is aligned with the axis of spindle 53. Rollers 59 are so mounted as to engage the rim angle 24 of the point and bear thereagainst as they rotate about their own axes and revolve around the axis of the point.

Due to tolerances in machine construction, it is diflicult to obtain exact alignment of the axes of point 15 and spindle 53. To prevent any eccentricity in the rolling of rim angle 24, I provide a floating connection between spindle 53 and head 58 which permits the head to align exactly with the axis of point 15. Threadedly connected to the lower end of spindle 53 is a holding socket or nut 61 which is internally opened to form a circular chamber 62. Mounted loosely within chamber 62 and spaced downwardly from the bottom of spindle 53 is the head 58 which is of cylindrical shape having an outwardly flared upper portion 63. A complementa-l inwardly beveled flange64 on nut 61 prevents head 58 from falling out of chamber 62, and tends to center the head when the latter drops downwardly.

Between head 58 and spindle 53 is a flat circular retainer plate 65 in which are mounted a plurality of balls 66 which serve to transmit thrust loads between the spindle and the head. To rotate head 58 with spindle 53 spaced driving cleats 67 are extended downwardly from the spindle and engaged loosely in slots 68 formed in plate 65. Similar driven cleats 69 extend upwardly from head 58 and engage in slots 70 as is best seen in Fig. 7. By this arrangement, head 58 may shift slightly from side to side and incline from the vertical while remaining rotatably connected to spindle 53.

The particular arrangement of rollers 59 upon head 58 is very important and may best be understood by considering Figs. 8 and 9. The bottom surface of head 58 is defined by a plurality of inwardly and downwardly in of the surfaces 72. Blocks 73 are of elongated rectaii gular shape and rotatably support rollers 59 by means of central pin 74 which extends exactly perpendicular to the upper or seating surface of the block. Preferably, rollers 59 are mounted on anti-friction bearings and have a hardened and highly polished outer surface. To attach blocks 73 to head 58, individual fastening bolts 75 are threaded-upwardly into the head near the outer ends of the blocks. This, of course, also permits convenient replacement of the rollers.

While the holding blocks 73 lie flat against the surface 72, they are not directed exactly toward the axis of head 58 as can be seen from an inspection of Fig. 9. Rather, each block 73 is ofiset slightly or advanced in the direction of rotation from the center of its supporting plane 72, and directed slightly to the side of the head axis with all of the blocks being oifset in the same direction and in the same amount to provide a symmetrical arrangement. In other words, a plane which is passed through the axis of each roller 59 and the longitudinal centerline of block 73 is parallel to, but offset or spaced from the plane which is passed radially through the axis of nose 58 and the center of the surface 72. The effect of this is to shift the axis of each roller 59 out of any plane passed through the axis of head 58, and to incline each roller at, what I define as a compound angle with the axis of point 15. Accordingly, the line or element of contact between the surface of rollers 59 and the rim angle surface 24 is inclined in two directions from the axis of the point. This is the same as saying that since the axis of the head 58 and the axis of the roller 59 do not lie in a single plane they cannot be relatively positioned by reference to a single planar angle between them.

As will be remembered, the axis of pen point 15 is held coaxially with that of head 58. Accordingly, the rim angle surface 24 is a surface of revolution traced about the axis of head 58. Also, it can be seen that rotation of head 58 causes rollers 59 to revolve around the head axis in a path which is a surface of revolution thereabout. Because the rollers 59 are geometrically formed concentric with their own axes it can be appreciated that the contact between the surfaces of the roller is not a pure rolling engagement, but includes a component of sliding engagement.

The effective relationship of rollers 59 to rim angle surface 24 is best seen in the diagrammatic views Figs. 10 and 11. The line of contactbetween the surface of rollers 59 and rim angle surface 24 is tilted out of the vertical plane back away from the axis of rotation of the rollers. The amount of inclining is indicated by the angle A in Figure 11. The offset between the plane passed radially through the axis of point 15 and the plane passed through the axis of roller 59 is represented by the distance X this being the offset distance as was described in the next to preceding paragraph.

As viewed in Figure 11, the rollers 59 would be revolved around the point 15, in a clockwise direction as seen from above, by rotation of head 58 about its own axis. Since rollers 59 are free to rotate about their own individual axes they would at the same time rotate in a counterclockwise direction as seen from above.

In the operation of the device, the angular relationship just described, and the direction of rotation is such as to cause rollers 59 to tend to ride up the surface of rim angle 24 toward rim lip 25. That is, as rollers 59 rotate about their own axes and revolve about the axis of point 15, they slip or slide frictionally down the surface of rim angle 24 as well as rolling along the circumference thereof. The pressure exerted by rollers 59 on rim angle 24 tends to thin the material of the rim wall and cause it to expand outwardly from ball 17. This produces the desired amount of clearance in metering section 28. At the same time, the component of downward sliding motion of rollers 59 prevents any upward flow of material toward rim lip 25. Thus the finished point has the desired clear- 7 ance without any distortion of the smooth and regular surface of rim lip 25. V I

While I have thus shown and described in some detail my method of finishing a ball pen point and a preferred form of apparatus to accomplish the method, it is to be understood that changes of design and construction can be made without departing from the scope of the invention. Therefore, I do not Wish to be limited by the foregoing except as defined in the appended claims.

I claim:

1. In a method of producing a desired clearance between a ball and the inner walls of a cavity in the nose of a member in which said ball is held the improvement which eliminates marring of the surface of the ball and maintains a smooth lip on the rim of said nose consisting of the steps of: applying pressure at spaced points about the rim of said nose by direct contact through pressure applying surfaces with said rim alone; rotating said pressure applying surfaces about an axis which is non-planar with the longitudinal axis of said nose; and simultaneously revolving all of said pressure applying surfaces about said axis in a direction to expand said rim away from said ball and resist the flow of rim material towards said lip.

2. In a method of forming a ball pen point wherein a ball is pressed into a cavity formed in the nose of the point, the rim of the point is folded over to retain the ball, and a desired clearance is produced between the ball and the inner wall of the nose the improvement which consists in the steps of: applying a pressure in direct contact with the ball to seat said ball in the nose cavity; simultaneously applying a pressure in direct contact with the nose rim to partially fold said rim radially inwardly against the ball; subsequently applying a pressure in direct contact with the nose rim alone to finish folding said rim inwardly against the ball to the desired rim angle; applying pressure at spaced points about the rim of said nose by direct contact through pressure applying surfaces with said rim alone; rotating said pressure applying surfaces about an axis which 'is non-planar with the longitudinal axis of said nose; and simultaneously revolving all of said pressure applying surfaces about said axis in a direction to expand said rim away from said ball and resist the flow of rim material towards said lip.

3. In a method of producing a desired clearance between a ball and the inner walls of a cavity in the nose of a member in which said ball is held the improvement which eliminates marring of the surface of the ball and maintains a smooth lip on the rim of said nose consisting of the steps of; applying pressure at spaced points about the rim of said nose by direct contact through pressure applying surfaces with said rim alone, rotating each of said pressure applying surfaces about an individual axis which is non-planar with the longitudinal axis of said nose; and simultaneously revolving all of said pressure applying surfaces about said axis in a direction to expand said rim away from said ball and resist the flow of rim material towards said lip.

References Cited in the file of this patent UNITED STATES PATENTS 1,798,738 Hoern Mar. 31, 1931 2,167,654 Hothersall Aug. 1, 1939 2,216,878 Densmore Oct. 8, 1940 2,234,182 Lauer Mar. 11, 1941 2,257,566 Lewis Sept. 30, 1941 2,414,598 Klipper Jan. 21, 1947 2,498,009 Schrader Feb. 21, 1950 2,646,761 Knobel July 28, 1953

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