US2075725A - Writing instrument - Google Patents

Description

March 30,1937. v D, KA 2,075,725

WRITING INSTRUMENT Filed Oct. 18, 1935 awe/WM,

Patented Mar. 30, 1931 PATENT OFFICE- 2,015,725 wnrrmc. nes momnr David Kahn, -Woodcliif, N. J., assi gnor to Davin Kahn, Inc.-, North Bergen, Hudson County, N. J a corporation oi. New Jersey Application October 18, 1935, Serial No. 45,663'

13 Claims.

This invention relates to mechanical pencils and has special reference to a novel construction of the tips and barrel portion 01 such pencils and to themethod of connecting such a barrel and tin. s

In the construction of pencils of this'type, it is common to employ a metal tip and a barrel of plastic material such as celluloid, pyroxylin, cellulose acetate and the like. .These barrels are usually quite thin and much difliculty has been experienced in firmly uniting the barrel and tip. Attempts have been made to'overcome this difflculty in various ways. For instance, it has been proposed to provide the tip with a threaded, upper end and to screw the barrel thereon. Such a construction is not only expensive but also,

due to the thinness of. the barrel, frequently rewhich is provided with a circumferential groove In' carrying out the present invention, it is proposed to utilize the natural flow property otbarrel materials of the kind mentioned when in the form of thin tubes and particularly to use this flow when the material-has been softened as by a suitable solvent or by heat, the tip being provided with one or more circumferential grooves into which the barrel material will flow.

One important object of the invention is, therefore, to form an improved joint between the tip and barrel of a mechanical pencil wherein theparts are held together without the use of threads or of a molding method. v

A second important object oi .the invention is to provide a novel tip and barrel joint for mechanical pencils, wherein the inherent tendency of the barrel material to how is utilized to'cause a portion of such material to interlock with'circumferential grooves formed on the of the tip.

A third important object of the invention is.

to provide a novel method of forming a rigid 55 joint between the tip and barrel of such a pencil p r part upon the barrel material having been softened by suitable treatment.

With the above and other objects in view, the invention consists in general of certain novel details of construction and combinations of parts 5 and of a process including certain novel steps,

. all of. which is hereinafter fully described and particularly 'pointed out in the claims.

In the accompanying drawing, which shows certain preferred embodiments of the invention, 10

- like characters of reference indicate like parts in theseveral views, and:-- I

Figurel is a section taken axially through the lower part of one form' of the invention showing its use in connection with a pencil ar- 15 rangedto be operated by rotation of its upper end with respect to the barrel.

- Figure2 is a similar view of a pencil showing. the use of the invention in connection with a pencil operated by rotation of the lower part of 20 the tip structure with respectj to the barrel.

Figure 3 is a section on the line 3-3 of Figure 2.

Figure 4 is a greatly enlarged detail section of a portion oi. Figure 1 to show the joint.

Figure 5 is similar greatly enlarged detail of a portion of Figure 2. A

Figure 6 is a detail showing one modification of the joint.

Figure. 7 is a'detail showings. second modiflca- 30 tion of the joint.

Figure 8 is a detailed section through the tip in one form of the invention.

Figure 9 is a side elevation of a certain collar as used herein."

In the forms of the invention shown in Figs. 1 and 2, there isdisclosed the usual spiral actuatlng tube l0, runner tube ll, carrier lug l2 and ejector lug I3, these parts corresponding in construction and function to the similar parts shown 40 in the Patent No. 2,009,182, granted July 23, 1935.

In pencils of this type the runner tube is fixed in the'tip and the actuating tube is revoluble with respect to the runner tube for protracting .ind retracting the lead. Since these elements do not form part of the-present invention, no

further description of them is deemed necessary.

The form of the invention shown in Figure 1 illustrates that type of pencil wherein the oper'ation is eifected from the upper end and the,- actuating tube-rotates in the barrel. In this type of pencil, there is provided a .tip' havlnga conical body I4 and a reduced upper part or neck l5, 7

E which is immovable with respect to the lower part reduced upper portion or neck I9 which is revolubly connected to the lower part I8 in the manner common to tip-operated mechanical pencils. Also in this form the actuating tube is fixed to the neck I9 as by a lug 20 struck out from the actuating tube and engaging ina notch 2I formed in the upper end of the neck. On the neck is fitted the barrel 22.

Considering the manner in which the barrel is secured to .the neck in accordance with this invention, it will be seen that in Figure 1 the neck I5 is provided with a circumferential groove 23, the exterior being otherwise smooth, while in Figure 2 the neck is similarly provided with a circumferential groove 24, but the neck is roughened in any suitable manner, such as by knurling In the form shown in Figure 6, the neck I5 is provided with a series of circumferential grooves 26 and in Figure 7 the neck is not only provided with a series of grooves 21 but the ribs 29, 29a and 29b defined by these grooves are roughened in any suitable manner as by knurling 28.

In all of these forms, it will be seen that the barrel material projects slightly into the grooves and this is accomplished in the following manner. The tubular formed barrel is suitably treated to soften its lower end. This softening may be effected in any desired manner, such as by heat, which will not only s'often the material, but tend to expand it slightly. Alternately, the lower end of the barrel may have a suitable solvent, such as a ketone exemplified by acetone, applied thereto, preferably interiorly of the barrel. This softened end is slipped on the neck to butt against the neck shoulder and is allowed to harden in this position. As the softened end is forced on the neck, some of the softened material will fiow into the groove or grooves to interlock therewith.

Some of the softened material interiorly of the tube end will also interlock with the knurled portions 25, as shown in Figures 2 and 5, or 28, as shown in Figure 7. In that form of the invention in which knurling is employed, the grooves '24 and 21 provide a primary tip means assisting in locking the barrel to the tip member and the knurling or 28, a secondary tip means for locking the barrel to the tip member. The knurling in effect forms a series of fine grooves into whichflows material interiorly of the barrel which has been softened by the application of a suitable solvent, this material forming ribs extending into fine grooves formed by the knurling. In this connection, it is desired to point out that any suitable chemical or composition may be used which accomplishes the softening of the barrel. More specifically, any of the prior art solvents which are used for softening pyroxylin, celluloid cellulose nitrates or cellulose acetates, are suitable. The prior art solvents are, therefore, by the above statement incorporated as part of the present disclosure.

The tube may also be prepared by coating its end interiorly with a cement suitable forthe material from which the tube is made, the materials above named being such that cements suitable for them have a solvent action on the material.

The coated tube is then fitted on the neck as before and the cement allowed to set. This will effect the formation of a rib or ribs extending transversely of the pencil barrel and interlocking with the transverse grooves of the tip member, and other ribs extending interiorly and longitudinally of the barrel tube when the tip neck is knurled, as shown at 25 and 28, the longitudinal ribs interlocking with the fine grooves extending longitudinally of the tip neck and formed by the knurling. It is, of course, within the province of the present invention to provide the neck member portions I9 with coarse knurling, or stated differently, with a series of somewhat deeper grooves extending longitudinally of the tip neck, the softened interior portion of the barrel flowing into said grooves to form longitudinal ribs extending interiorly and longitudinally of the barrel.

In the form of the invention shown in Figure 7, all of the ribs 29, 29a and 29b may be knurled and therefore provided with longitudinally extending grooves, or only some of the ribs may be knurled and others left unknurled. For exam ple, the rib 29a may be unknurled and ribs 29 and 29b knurled, or both 29a and 29b may be knurled and 29 remain unknurled, or 29 and 29a may be knurled and 29b left unknurled. This provides,

either a three-point longitudinal attachment, or a two-point 0r one-point longitudinal attachmentof the barrel to the pencil tip- Instead of interiorly coating the lower end of the celluloid or pyroxylin tube, celluloid cement or the like containing a solvent capable of softening the interior of the tube may be applied to the neck members I5, I9 and allowed to flow into the grooves 23 or 24 or into grooves 26 or 21.

The cement will, of course, flow into the fine grooves formed by the knurling 25 or 28. When,

the tube is fitted over the neck, the solvent present in the cement will act on the interior of the tube and the softened interior tube material will fiow into the transversely extending grooves formed on the neck member and the longitudinally extending grooves formed on the tip rib members where knurling is employed. The cement itself exerts a certain action in fixing the interior barrel to the tip member, and this is supplemented by the interlocking of the transversely and longitudinally extending barrel rib members with the transversely and longitudinally extending tip-neck rib members. Any cement may be used which will perform the function set forth, that is, will act to soften the interior of the pencil barrel and allow the material to flow into the grooves.

The tube forming the barrel maybe forced on the'tip neck without softening when the material is of such a character that it will expand over the ribs of the neck and flow to some extent into the groove or grooves. In other words, advantage c-an be taken of the natural flow tendencies of some of these materials. However, since the materials are made of different ingreclients, by different chemical processes, under different pressures, and'therefore vary in stability; the best method is to soften the interior of the tube in accordance with the present invention. However, as indicated in some casesif the tube is not softened when it is forced over the neck the material will expand over the ribsand engage in the transverse grooves of the tip member and to some extent into the fine longitudinal grooves formed by the knurling.

It is to be noted that in accordance with the,

present invention, a preformed tube is used for the barrel and that the barrel is not molded onto the neck. As clearly shown in Figure 8, the tip l8 has a recess 30 wherein the lower part I! of the member l9 extends. Furthermore, this recess ll is chamfered as at 3| to receive the lower end of the plastic tube IT, as shown in Figure 5.

Also, it will be noted that the member I! has in both ends chamfered as at 32, the upper chamfer serving to guide the tube onto the larger portion of the member, and a similarchamfer "is provided on the member It, as shown in Figures 1 and 2.

While the plastic material has been shown as extending rather far into the grooves of the various forms, it is to be un erstood that the illustration is exaggerated in rder to bring out this feature, and that the plastic material may merely extend far enough into these grooves to form a secure lock for the tube and member I! or J9, as the case may be.

' The locking ribs are formed after the tube is forced over the neck of the tip, and, therefore, are formed in place, or may be termed in situ" formed ribs, which broadly provide an in situ formed portion of the barrel extending into the tip-locking means. i

The present invention, while particularly applicable to mechanical pencils, may be applied to any writing instrument where the same problem is involved.

Instead of using acetone as a softening medium, ethyl alcohol, methyl alcohol, ethyl acetate or amyl acetate may be used.

I claim:-'-

1, The method of forming a joint between a writing instrument tip and a pro-formed barrel of plastic material adapted to flow when softened,

40 said tip being provided with means for receiving said softened material, said method comprlssoften the interior of said barrel end, seating the tip carrying the cementin the end of the barrel whereupon said cement softens the barrel end and permits the softened material to flow into the material-receiving means, and hardening the softened portion of the tube whereby the barrel is fixedly secured to the tip.

3. That method of forming a joint between the tip and barrel of a mechanical pencil comprising providing the tip with a circumferentially grooved neck portion, providing a preformed barrel of plastic material and having an end proportioned to fit closely.pn said neck, applying a solvent cement to the interior of one end ofthe barrel. seating said neck in the cemented end of the barrel whereby the cement will enter the neck groove, and allowing the cement to set.

4. In a mechanical pencil, a tip member having its upper end reduced to form a neck, said neck being provided with transversely and longi- 76 tudinaiiy extending grooves and a preformed barrel of plastic material fitted over said neck and having transversely and longitudinally extending in situ formed ribs interlocking with said transversely and extending grooves.

6. In 'a mechanical pencil, a preformed barrelof plastic material, and a tip having its upper end reduced to form a neck, said neck having tip means for locking the barrel thereto, one end of said barrel fitting tightly over the neck with an in situ formed portion of the barrel extending into said tip-locking means.

, 7. In a mechanical pencil, a preformed barrel of plastic material, and ,a tip having its upper end reduced to form a neck, said neck having tip means for locking the barrel thereto and at least a' portion of its surface roughened and in contact with said barrel, one end of the latter fitting tightly over the neck with an in situ formed portion of the barrel extending into said tip-locking means. I 1

8. In a mechanical pencil, a preformed barrel of plastic material, and a tip having its upper end reduced to form a neck, said neck having tip means for locking the barrel thereto, one end of said barrel being cemented to and fitted tightly over the neck with an in situ formed portion of the barrel extending into said tip-locking means.

9. In amechanical pencil, a preformed barrel of plastic material, and a tip having itsupper end reduced to form a neck, said neck having tip means for locking the barrel thereto and atleast a portion of its surface roughened and in contact with the barrel, one end of the latter being cemented to and tightly fitted over the neck with an in situ formed portion of the barrel extending into the tip-locking means.

10. In a mechanical pencil, a preformed barrel of plastic material and a tip having its upper end reduced to form a neck,.said neck being provided with a series of alternate circumferential grooves and ribs and fitted in one end of the barrel, said barrel being cemented on said neck with the cement entering said grooves.

11. The steps in the process of making a writing instrument having a barrel of material capable of being softened and a metal tip having a roughened surface, comprising ,forming the said barrel, adding a softening material for the barrel to the interior surface thereof and seating the said metal tip in the interior of the barrel so that the inner surface of the barrel will shape itself the said barrel and tip. 12. In a writing instrument, the method of I forming a joint between a plastic and metal portion thereof comprising roughing the metalportion, adding a solvent for the plastic to the surface of the plastic portion thereof in a quantity such that thesection of the plastic material in close proximity to the surface will be solubilized, contacting the metal portion with the plastic portion and solvent in rder to cause the surface of the plastic portion 0 conform to the shape of the. plastic material shall become plasticlzed and tend to mold itself to conform to the shape of the said serrations, and allowing the cement to harden to form a joint between the tip and barrel.

DAVID KAI-1N.

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