US 2834321 A
Description (OCR text may contain errors)
May 13, 1958 G. DUEFRENE BALL-TYPE WRITING TIP Filed Nov. 9, 1954 IN VENTOR Que/Fen? Geo/ye MB kg a LO ATTORNEYS nited States Patent BALL-TYPE WRITING TIP George Duefrene, Stepney, Conn.
Application November 9, 1954, Serial No. 467,755
3 Claims. (Cl. 120-424) This invention relates to ball point pens, and more particularly to ball-type writing tips for such pens.
An object of the invention is to provide an improved ball-type writing tip which is simple and economical to manufacture, extremely rugged and sturdy, and reliable over an extended period of use.
As made at the present time, ball point pens comprise an exterior barrel member having a clip, and a refill cartridge for the barrel, comprising an ink tube and an attached ball-type writing tip. The writing tip is in the form of a tubular metal member which holds the applicator ball, and is fabricated as a separate assembly and attached to the ink tube after fabrication by a separate operation.
It has been the practice in the past to fabricate the tubular members of the writing tips by screw machines, either from solid rod or tubular stock which is drilled and counterbored to the desired shape. This is a relatively slow and costly procedure due in part to the large amount of stock which has to be removed.
In these writing tips the applicator balls are of relatively small diameter, and require the maintenance of close tolerances in the socket of the tubular member, where the ball is carried. When, as heretofore practiced, the writing tip was fabricated by a screw machine operation, the maintenance of the required close tolerances became troublesome and costly, and at times entire lots of parts had to be discarded because the dimensions were not accurate and could not be corrected.
The above difficulties and disadvantages of these prior, machined writing tips are obviated by the present invention, by the provision of a novel and improved balltype writing tip comprising a sheet metal shell having an integral, transverse bottom wall, which shell'may be quickly and economically formed in high production equipment as for example in an eyelet machine. By the use of die-forming processes, especially where small diameters are involved, a high degree of accuracy may be readily attained and held throughout large production runs. Moreover, with the present invention, in producing the sheet metal writing tips a novel method of assembly is utilized by which the applicator ball is assembled to the tubular writing tip member by a quick and economical press operation; this method not only provides for quick assembly but also tends to correct whatever dimensional variations might be present in the components.
Prior to the assembly of the applicator ball to the writing tip shell the transverse end wall of the latter is in-' wardly dished to provide an outwardly-open socket, and preferably the side walls and transverse end wall are constricted or fluted for strengthening purposes and also to provide a backing for the socket. When the applicator ball is pressed into the socket, it reforms the latter to substantially a hemispherical shape, and during this operation axial force is also applied to the rim of the socket, constricting and closing-in the rim so as to hold the ball captive. Not only is this structure and method quicker and more economical than the screw machine process, but the resultant reinforced writing tip is so sturdy that it can withstand a very substantial blow without being materially deformed or rendered inoperative.
In several forms of the invention illustrated, the shell adjacent the socketed end is provided with a plurality of longitudinal flutes to provide for strength, said flutes rightly backing up the socket; in another form of the invention the shell is constricted annularly to strengthen it and back up the socket.
A feature of the invention resides in the provision of a novel and improved, ball-type writing-tip shell as above set forth, which will accommodate itself to diiierent sizes of applicator balls within a predetermined range, thereby broadening the tolerances permissible on the balls, with a resultant reduction in cost thereof.
Other features and advantages will hereinafter appear.
In the accompanying drawings:
Figure l is an enlarged, axial sectional view of a completed ball-type writing tip made in accordance with the invention.
Fig. 2 is an axial sectional view, enlarged, of a sheet metal shell illustrating a step in the method and construction of the improved writing tip.
Fig. 3 is a view like Fig. 2, but showing another 0p- I eration on the shell, illustrating an additional step in the method and construction of the writing tip.
Fig. 4 is a bottom view of the shell shown in Fig. 3.
Fig. 5 is a sectional view of the lower portion of the writing-tip shell and an assembly die carrying an applicator ball, this view illustrating the method of assembling the applicator ball to the shell.
Fig. 6 is a view like Fig. 4, but showing a different kind of fluting applied to the closed end of the shell.
Fig. 7 is a fragmentary sectional view of a writing tip, illustrating a modified form of the invention.
Fig. 8 is a side elevational view of an assembled writing tip and ink tube made in accordance with the invention.
Referring first to Fig. 1, the improved ball-type writing tip of this invention comprises a deep metal shell 10 having a large-diameter body portion 11 adapted to be press fitted into an ink tube, such as the tube 12 shown in Fig. 8. The shell 19 has a neck portion 13 of reduced diameter, terminating at its lower end in an integral transverse end wall 14. The end wall 14 is perforated, being provided preferably with a central opening 15 by which ink from the interior of the shell 10 can pass through the wall.
As shown in Figs. 1 and 2, the wall 14 has a substantially. hemispherical shape, being inwardly dished to provide an outwardly-open socket or recess adapted to accommodate an applicator ball 16, and the lower edges or rim 17 of the shell are constricted or turned in slightly below the horizontal equator of the ball 15, thereby to retain the latter and hold it captive at all times.
By the present invention the side walls of the neck portion 13 are constricted, being provided with longitudinal flutes 18 adjacent the transverse end wall 14, the lower ends of the flutes extending inwardly in contact with the end wall 14, as shown at 19 in Fig. 1, thereby to back up and reinforce the wall.
I have found that by the provision of the sheet metal shell 10 with integral, inwardiy-dished end wall 1d and constricted neck portion 13 as provided by the flutes 13, an extremely strong and sturdy construction is had, enabling the applicator ball 16 to be readily assembled to the neck portion by a simple and quick press operation which at the same time constricts the rim of the socket so as to retain the applicator ball in place.
Thus the complete writing tip may be economically produced by metal-forming, stamping and press operapine board by a hammer and thereafter extracted without rendering it inoperative or damaging it in any appreciable manner. It will be readily appreciated that if the pen in which the writing tip of this invention is incorporated were to be dropped on the floor, the blow would be less than that suffered by driving the tip into a board, and consequently such a pen could stand considerable rough usage without becoming inoperative.
The method of producing the improved writing tip of Fig. 1 is illustrated in Figs. 2 through 5. In Fig. 2 the shell 1012, which may be formed of sheet metal in any suitable manner, is shown as having a substantially cylindrical neck portion 13a provided with an integral, transverse, inwardly-dished end wall 14a having a central opening 15a. It will be readily understood by those skilled in the art that the structure shown in Fig. 2 may be produced, for example, by a series of drawing and stamping operations in an eyelet machine, without difliculty and with great facility. After the structure of Fig. 2 has been produced, I constrict the neck portion 13a by providing a plurality of flutes 18b, Fig. 3, in the side walls of neck portion and also in the transverse end wall labeled 14b in Fig. 3. The flutes 18b are readily shown in Fig. 4, and as a consequence of the flutes, the socket 20a provided by the inwardly-dished and fluted end wall 14b is somewhat triangular in its configuration.
Referring to Fig. the shell structure formed as shown in Fig. 3 is brought into operable relation with a die 21 having a conical recess 22 in which the applicator ball 16 is placed. The shell a is moved forcibly toward the die 21 to cause the applicator ball 16 to fully enter the socket a and reshape the socket so as to make it substantially hemispherical. At the same time, the conical walls of the die 21 will constrict and force inward the lower rim 17a of the socket 20a below the horizontal equator of the applicator ball 16, thereby causing the ball to be thereafter held captive in the socket. Due to the springiness of the sheet metal, upon removal of the force exerted by the die 21 the socket 2011 will enlarge slightly, sufliciently to free the applicator ball 16 for turning even under the lightest writing pressure. 1
I have found that the provision of the flutes 18b and the backing-up of the transverse wall 14b by the constriction of the neck 13a of the shell is of importance in providing the necessary strength and rigidity to the writing tip, and in enabling the quick and easy assembly of the applicator ball to the shell as above set forth.
Other forms of construction may be employed for the neck 13a of the shell 10a. For example, in Fig. 6, a total of six flutes 18c may be provided in the neck, in place of the three flutes 18b shown in Fig. 3. In Fig. 7 the neck 13b may have an annular construction 18d, backing up a transverse hemispherical end wall 146 in which an applicator ball 16 is held captive. It will be noted that in each instance the transverse end wall which constitutes the socket for the applicator ball 16 is backed up by formations of the side walls of the neck portion of the drawn metal shell.
Considering Fig. 5, if the applicator ball 16 is somewhat smaller than the specified size it will still function satisfactorily in the shell, for the reason that the press operation by which the ball is assembled reshapes the socket to the size of the ball and also constricts the rim of the socket in accordance with the size of the ball. Thus, within limits, variations in the diameter of the ball 16 may be tolerated without rendering the writing tip inoperative, and this is of importance in reducing the cost of the balls.
Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.
1. A writing tip for a ball-type pen comprising an ink applicator ball, a cylindrical tube having a sheet metal side wall and having integral with said side wall a sheet metal end wall doubling back on said side wall and extending into the tube, said end wall being so formed as to provide a semispherical socket having a radius to receive the applicator ball, said socket-forming end wall having an ink feed hole extending from the interior of the tube to said socket, the end of said side wall and the adjacent portion of the end wall extending inwardly to embrace and retain the ball in the socket, portions of the side wall of the tube extending radially inwardly and into engagement with portions of the socket-forming end wall to reenforce the latter against distortion when force is applied to the ball in the direction of the axis of the tube.
2. A writing tip as defined in claim 1, in which arcuately spaced portions of the side wall of the tube extend radially inwardly into engagement with the socket-forming end wall to reenforce the same.
3. A writing tip as defined in claim 1, in which all portions of an annular part of the side wall of the tube extend radially inwardly into engagement with the socketforming end wall to reenforce the same.
. References Cited in the file of this patent UNITED STATES PATENTS 2,646,761 Knobel July 28, 1953 2,700,784 DeBrock Feb. 1, 1955 FOREIGN PATENTS 239,050 Germany Oct. 7, 1911 819,954 Germany Nov. 5, 1951 1,003,293 France Nov. 14, 1951 663,361 Great Britain Dec. 19, 1951 511,872 Belgium June 30, 1952 514,617 Belgium Oct. 31, 1952 691,469 Great Britain May 13, 1953 887,924 Germany Aug. 27, 1953 UNITED STATES PATENT OFFICE CERTIFICATE 0 F QQRRECTION Patent No. 2,834,321 May 13, 1958 Ge or go Duefrene It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowu Column 2, lines '7 and 8, for "rightly read rigidly-m sigma and sealed this 15th day of July 1958,
(SEAL) Attest: KARL Hr, AXLIN ROBERT C. WATSON Commissioner of Patents