US2306494A - Mechanical pencil - Google Patents

Description

Patented Dec. 29, 1942 NIECHANICALYPENCIL Anton T. Otto and Victor'A. Strom,

Alameda, Calif.

Application July 28, 1941,5-Serial N 0.404 303 7'Claims. cine-18) This invention relates to improvements in me- :chanical :pencils :and more particularly to the crayonguiding'means thereof.

.Among the objects of the invention is the: provision of means to prevent the fouling. of the'feed mechanismbyz'tbrasions from the crayon.

I .eAnother. object is'tohold the :crayon within the vpencil without "exerting constrictive pressure against it. 7

Another object is to facilitate the reloading of the pencil.

Another object is to reinforcethe crayon against -warpin'gand breakage before itis loaded into the feed mechanism.

.Affurther 'object is to encase the crayon a I nonabrasive, nonabsorbentsheath that will protect it against the deleterious-effect of atmospheric temperature.

.Other; objects and advantages will appear as the description progresses.

. TCI'aYOIIS IfOI" marking :on glass, porcelain, metal and similar smooth and nonabsorbent surfaces are "composed 1 of :waxlike and highly adhesive ma- :terials. ."Such compositions have alstrong afiinity for themetals;plastics or other materials entering into- -the structures of mechanical pencils, in

holder. Because of its essentially adhesive-nature 'the sides of the crayon are=abraded by the con- --tacting tubular portion of the prior types of holders. *Such abrasion builds up on the walls of the guiding nipple to such an extent that the bore of "the nipplebecomes toosmall to receive or feed the=reloads"of crayon. "Such abrasions interfere 'withthe smooth feeding of the crayon as desired for markingpurposes. These disadvantages are overcome by the .use' of the present invention.

-Which "the1crayon'is push'ed outward from the 's'tructed and combined in accordance with;this

invention. M

Fig-:3 isan end view of1thezcrayoni-enclosing sheath.

In detail the construction illustratedin .the drawing, referring first to Figs 1,-5comprises-the tapered finger grip portion l; having the: integral tubular :reduced diameter. stem 2, center rbored throughout its length. :Thegfinger:gripportion I,

iscounterbored asiat 5'3, -;and hasthe internal thread 4- adj acent its outer end. Throughout its lengthtthe'stem I2 hasthaslot 5 extendingoutward from the center. bore.

.:The plunger *6 slides freely in this centerbore and: has-tWo .;interspaced transverse holes. therethroughne'arits rear end. The'wire helixj'l'encircles the stem 2 and is freely slidable thereon and 'has'its opposite .ends 8, 9, bent "inwardly through therslot-ili:to; engagethe holes in the end ofthe plunger 6. I

".The sleeve 11-0 encircling the stem '2, rotates freely? thereon: and is internally, threaded .to engagethe'helix 1. Rotation of :the :sleeve acting through the helix 7 advances or retracts the plungerit; within the stem.

'aThe head; 1 I has "its'dnner' end? bored to snugly i fitrthe: end: of the stem 2- protruding beyond the sleeve. "The1screw1'2 extends throughthe wall "Broadlystated' the invention consists in encas- 1 ing the crayon in an inexpensive sheath having a low coefficient of friction, such as waxed paper, but with suificient adhesive lubricating qualities to hold the crayon therein without abrasion.

In this specification and the accompanying drawing the invention is disclosed in its preferred tion of the crayon holding end of the same con- 55 convenience in j illustration .in Fig; '1. iThlSjSClBWI l2 also;passes throughthe band of thepocket clipl'4rencircling the head I l-an'd hav- "ingzthei ball endi l5' resilientlyl wb'earingl against the periphery of thesleeve ID. "The outer end oflthe of the head I lz'andithejstem land: is threaded in thez-plug. H which snugly fits thebore in' the stem.

.Bythisz means thezplugsactszwith the head of the screw to clamp'the 'hea'dtl lcsecurely onto the end of the stemr2. Inpracticethe screwlz, extends throughthe-slotifi to: engage the pluglf3; but for itzis. otherwise shown head II can .be bored to act as a receptacle for spare crayons, and is closed by the polygonal cap l6 screwed therein. The specific structure and mode of operation described is not essential to the functioning of the present invention, since it is applicable to the many types of mechanical pencils available and adapted to the extension of the crayon for the purpose intended.

The finger grip portion I, illustrated in enlarged detail in Fig. 2, is provided with the nipple l1, having its outer end tapered toward the end of the crayon [8. Intermediate its length it is externally threaded at H] to engage the internal threads at 4. It has the extension 20 of reduced diameter to leave the annular space 2 l within the counterbore 3. The end of this extension alines with the shoulder 22 forming the bottom of the counterbore, toward which it can be advanced by the threads 4l 9. This nipple has a center bore slightly greater than the diameter of the crayon. This difierence in diameters leaves clearance for the thickness of the sheath 23 enclosing the crayon I8, and snugly fitting within the centerbore of the nipple H. The inner end of this sheath is slit to form the tabs such as 24, see Fig. 3, extending beyond the end of the crayon.

To insert the sheathed crayon l8, remove the nipple and insert the sheath 23 therein from the rear, leaving the tabs 24 extended beyond the end of the nipple. Then push the extension into the front end of the finger grip portion; this will fold the tabs 24 backward against the outer diameter of the extension 20. Screwing the nipple into place clamps the tabs 24 firmly between the shoulder 22 and the inner end of the extension 20. Preferably the crayon is inserted in the sheath before it is placed in the nipple. Thus assembled the crayon I8 is alined with the plunger 6 and is fed outward by the movement of the plunger actuated by revolving the sleeve ID, to advance the helix 1.

After the plunger has been advanced to the limit to eject the remnant of the used crayon, the plunger is retracted and a new sheathed crayon is inserted in the nipple by the method described. Each sheath will outlast many crayons, which makes reloading the simple matter of inserting the new unsheathed crayon without removing the nipple I! from the holder, if preferred. When the sheath becomes worn the nipple H is unscrewed and a new sheath inserted as described.

If desired the end 6' of the plunger 6 may be made concave to scrape the inner bore of the sleeve free from any unevenness or abrasions from the crayon, which may occur due to oversize or uneven crayons. It has the further advantage that it will not mushroom the head of the crayon when softened by heat.

The sheath 23 is preferably formed of helically wound paper tubing, such as drinking straws, heavily impregnated with hot parafiin or other waxlike liquids. When properly set this impregnating material presents a lubricated surface to the advancing crayon without any abrasive effect against it. Yet such a surface presents sufficient adhesiveness to prevent the movement of the crayon within the sheath, except by the force of the plunger 6. It is also sufficiently adhesive to prevent the crayon turning within the sheath during the act of marking with the crayon. The cushioning effect of the fibrous flexible sheath interposed between the crayon and the end of the metallic nipple minimizes scoring and breakage of the crayon at this point under the lateral pressure of marking.

If the sheath 23 is long enough to project a short distance from the end of the nipple H, as in Fig. 2, it prevents the metal nipple I! from scratching the surface being marked. This is an advantage in marking aluminum parts of airplanes and other easily scratched surfaces requiring the use of such crayons.

Having thus described this invention what is claimed and desired to secure by Letters Patent l. A crayon surrounded by a sheath of impregnated material, for use in mechanical pencils adapted to hold said sheath against movement relative to said crayon, while advancing said crayon.

2. A mechanical pencil including a tubular sheath lined with a wax-like lubricant and adapted to guide a crayon therein; and means for advancing the crayon through said sheath.

3. A mechanical pencil including a nipple adapted to guide a crayon therein; means for advancing the crayon through said nipple; and a sheath interposed between said nipple and crayon and having lubricating qualities with respect to said crayon.

4. A mechanical pencil including a nipple adapted to guide a crayon therein; means for advancing the crayon through said nipple; and an impregnated sheath fixed in said nipple between said nipple and crayon.

5. A mechanical pencil including a counterbored finger grip portion having a crayon guiding nipple therein; an impregnated sheath within said nipple and having one of its ends clamped between the end of said nipple and an abutment on said finger grip portion; and mean for advancing a crayon through said sheath.

6. A mechanical pencil including a counterbored finger grip portion; a crayon guiding nipple threaded in said portion and having a reduced diameter extension with its end engageable with an abutment in said counterbore; a sheath of flexible material within said nipple and having its inner end clamped between the end of said extension and said abutment; and means for advancing said crayon through said sheath.

7. A mechanical pencil including a counterbored finger grip portion; a crayon guiding nipple threaded in said portion and having a reduced diameter extension with its end engageable with an abutment in said counterbore; a tubular sheath of flexible material within said nipple and having tabs on its inner end. folded back over said extension within said counterbore; and means for advancing a crayon through said sheath.

ANTON T. OTTO. VICTOR A. STROM.

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