US2883967A - Mechanical pencil - Google Patents

Description

A. J. TESSIER MECHANICAL PENCIL Filed March 17, 1958 April Z8, 17959 INVENToR. A r arf/z J 77e S s z'er 56 5 7 A'TTORNEYS.

BY/jm/w lw I United States Patent Oiice 2,883,967 Patented Apr. 28,1959

MECHANICAL PENCIL Aram J. Tessier, Warwick, RJ., assignor to T. e T. Manufacturing Co., Warwick, R.I., a partnership Application March 17, 1958, Serial No. 721,946

1 Claim. (Cl. 1Z0-18) This invention relates to mechanical pencils.

A common form of mechanical pencil is provided with a lead carrier tube, a guide tube therefor, a screw for advancing the lead carrier tube, and a shell or barrel which encloses the foregoing and other parts which are essential and peculiar to the particular design of mechanical pencils. In many types of mechanical pencil constructions, the barrel of the pencil performs the function of a grip and a metal tip screw fastening secures and holds the barrel and working parts in assembled relation.

An object of the invention is to provide a mechanical pencil so constructed as to eliminate the above-mentioned metal tip fastening.

Another object of the invention is to utilize the resilience of parts of the pencil to effect the securing of the barrel and working parts in assembled relation.

Another object of the invention is to hold the barrel and working parts inassembled relation by providing a barrel, the bore of which will yield, to allow the passage of a lock shoulder therethrough to be engaged upon the recovery of the said bore.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claim.

In the accompanying drawings:

Figure 1 is an elevational view of a mechanical pencil embodying the invention:

Figure 2 is an elevational view of the inner working part assembly of the pencil of Figure l;

Figure 3 is an enlarged central longitudinal sectional view of the lower end portion of the pencil;

Figure 4 is a similar enlarged view partially in section and with the barrel omitted so as to expose certain inner parts of the pencil mechanism;

Figure 5 is a central longitudinal view of a fragmentary portion of the lower end portion of the pencil barrel;

Figure 6 is a similar view and showing the lower end portion of the pencil inner mechanism inserted within the barrel and prior to forcing the lower extreme end portion of the mechanism through the barrel; and

Figure 7 is a View of a modified pencil tip construction.

Referring to the drawing in more detail, and purely by way of example, 10 designates a mechanical pencil having an outer shell or barrel 11 which encloses the inner working mechanism 12 (Figure 2) of the pencil. This mechanism 12 (Figure 4) is the cap and barrel actuating type and therefore includes a lead carrier tube 13, a guide tube 14 therefor, a lead expeller rod 15, and a screw 16 for advancing and retracting the lead carrier tube 13 and lead expeller rod 15. A resilient clutch 17 is provided at the lower end portion of tube 13 for holding the lead 18, this clutch `being provided by splitting the end of the'tube 13 as shown and then slightly squeezing the split portions to reduce the bore of the tube to a size to grip the pencil lead. The other end portion of tube 13 has a projection 19 which extends through slot 20 in guide tube 14, and into the helical groove 21 of screw 16. The lead expeller rod 15 is slidably received in tube 13 to engage against the inner end of lead 18 and has a projection 22 at the other end of rod 15 which likewise extends through slot 20 into helical groove 21, and is spaced from projection 19, a distance equal to one-half the lead of screw 16.

A metal tip 23 is provided with a plurality of bore portions 24, 25, 26 and 27 which extend in step relation' with each other with the bore portion 24 of larger diameter being uppermost and rotatably receiving the screw 16. The guide tube 14 is received in bore portion 25 and is frictionally held therein against relative rotation with tip 23. A thin metal tube 28 encloses the screw 16 and is enlarged at one end so as to frictionally receive a bush 29 that frictionally engages screw 16, thus providing friction tight engagement between these parts. The bore of lbush 29 is of a friction tight coupling so that the screw and tube will turn together. The bush 29 extends beyond sleeve 28 to engage against a thrust washer 30 which is interposed between said bush and the adjacent end of tip 23. The foregoing description of the pencil mechanism is intended to be one example of a barrel action with which the present invention is primarily concerned and therefore equivalent actions may be used.

According to the present embodiment of the invention, the outer configuration of tip 23 (Figures 3 and 6) is made so as to provide three tapered portions 35, 36 and 37 of different diameters and all converging toward the lower end of the tip, with the tapered portion 35 of larger diameter being at the upper end of the tip. The portion 37 of smaller diameter is at the lower end of the tip and forms at the junction with the tapered portion 36, a shoulder 38. A cylindrical portion 39 is interposed between portions 35 and 37 and is of a diameter substantially equal to the diameter of the portion 35 at the small end thereof. The surface of portion 39 is provided With a plurality of axially extending splines 40 and the larger diameter of portion 36 is made slightly smaller than the doiameter of said portion 39.

As previously mentioned, the foregoing described mechanism is enclosed in the barrel 11 which is made of a hard rubber type material or a synthetic plastic material, as for example, polyethylene which will yield under pressure and recover upon the pressure being removed. The barrel 11 (Figure 5) has a bore 41 therethrough which is of a diameter slightly larger than the diameter of the tube 28 at the bush 29. The lower portion of bore 41 has three sections: a tapered bore portion 42 which angularly conforms to tapered portions 35 but is made slightly smaller in diameter, a reduced bore portion 43 which conforms to cylindrical portion 39 and is made slightly smaller in diameter, and a tapered bore portion 44 which conforms to the tapered portion 36 of the `tip 23.

In assembling the bar-rel 11 to mechanism 12, the said mechanism is inserted into the barrel at the upper end thereof. Upon sliding the same for the portion 39 to engage the -bore 43, the spline 40 Will cut through the wall of bore portion 39 to be embedded therein. As will be seen in Figure 6, the large diameter of tapered portion 37 is larger than the small diameter of bore portion 44 and upon forcing the said portion 37 through the bore portion 44 the wall thereof will be distended and increase the size of the opening to allow the passage of said tapered portion 37. Upon the passing of portion 37 beyond the end of the barrel 11, the wall portion of bore 44 will recover and engage at the rear of shoulder 38 and lock the barrel and mechanism 12 together against separation. The frictional engagement of portion 35 against wall of bore 42 and the engagement of the embedded portion 39 in the wall of bore 43 connects the barrel 11 and the metal tip 23 together for rotation. The metal tube 28 extends a substantial distance beyond the vbarrel 11 and snugly received thereon is a cap portion 45 which permits rotation of the said tube 28 relative to the barrel lll.

From the above, it will be apparent that by holding the barrel 11 against rotation and rotating cap portion 4S, the lead carrier tube 13 and expeller rod 15 will move axially in one or the other direction depending upon the direction of rotation of cap 45 relative to the barrel 11. It will also be apparent that the manner in which the tip 23 and barrel 11 are secured together eliminates the heretofore separate fastener tip.

In some instances it may be desirable to arrange for the tip portion 37 to be resiliently compressible so as to permit the barrel 11 to be made of less resilient material. To this end the portion 37 may be split axially as at 46 for a length suicient so as to allow the portion 37 to contract and be passed through the bore portion 44 and thereafter recover so as to engage shoulder 38 with the end extremity of said barrel 11.

I claim:

In a mechanical pencil having a lead propelling mechanism including a tapered tip at one end thereof, said tip being solid metal with a lead receiving and clutch tube bores therethrough, a barrel for said mechanism, said barrel bein elastic and having a bore therethrough in which said mechanism is received, said bore having a tapered portion extending inwardly from one end of the barrel with the small diameter of said tapered bore portion being at the end extremity of said one end, said tip being secured to said barrel for rotation therewith and having an annular shoulder of larger diameter than said small diameter, the external diameter of the end extremity of said barrel being substantially equal to the diameter of said shoulder, said tip extending through said tapered portion and said annular shoulder extending into engagement with the said end extremity of said barrel, said barrel being deformable when stretched by the solid tip to allow said shoulder to be passed outwardly through the said tapered portion at the said small diameter thereof, the barrel end recovering when passed beyond the said annular shoulder.

References Cited in the tile of this patent UNITED STATES PATENTS

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